Hub for syringe, connecting structure of hub, syringe, piston, needle assembly unit, connecting structure between needle assembly unit and syringe, syringe assembly and method of assembling syringe assembly

ABSTRACT

A syringe assembly has a hub body which can be inserted into a hub insertion hole and pulled out thereof into inside a sringe body. A chamfer portion is formed at the hub body, being capable of engaging with the hub insertion hole. A needle insertion hole capable of having a needle inserted therein is provided with an end face of the hub body in a direction of an axis center of the hub body. A flow hole is provided with the hub body such that the needle insertion hole and an inside of the syringe body are communicated with each other in the direction of the axis center. A piston engagement hole is provided on end face side of the hub body, so as to engage with the piston. A seal taper is annularly formed at the hub body, such that its outside diameter is made narrower for the end face side, so as to abut on and contact with an inner face of the hub insertion hole.

This is a continuation of application Ser. No. 08/263,752, filed Jun.22, 1994 now abandoned.

BACKGROUND OF THE INVENTION

This invention relates to a hub for a syringe, connecting structure ofthe hub, the syringe, a piston, a needle assembly unit, connectingstructure between the needle assembly unit and the syringe, a syringeassembly and a method of assembling the syringe assembly, suitable forapplying to a throwaway syringe assembly.

Since patient's blood included pathogenic bacteria adheres to a needleof a syringe assembly used, many throwaway syringe assemblies have beenused for preventing secondary infection.

A conventional throwaway syringe assembly is disposed so as to discardafter use. However, since it is necessary to remove a danger ofsecondary infection generating through the wound of a hand or the likeby a needle attached a patient's blood and the like thereto when thesyringe assembly is dealt with, the needle is cut from the syringeassembly with scissors or the like after use, and after that, they arediscarded.

However, the handling operation of a conventional throwaway syringeassembly requires a long time since it is necessary to handle it withreligious care so as not to hurt a hand or the like with the needle justafter its use till the needle is cut.

In addition, the cutting operation of a conventional throwaway syringeassembly to be executed before disposal is troublesome.

Then, the throwaway syringe assembly, capable of maintaining safety justafter use by inserting a needle into a syringe of the syringe assemblyjust after use using a screw or the like, and omitting cutting operationof a needle, has been proposed. However, the assembly and the operationof the proposed syringe assembly are difficult since its structure iscomplex.

It is preferable to use a syringe assembly more widely in such a mannerthat according to use, a plurality of kinds of needles are selected fora syringe or a plurality of kinds of syringes are selected for a needleso as to connect just before injection action at a site of treatment.However, it is difficult to easily insert a needle and a hub forconnecting a needle with a syringe into a syringe at a site of treatmentin a conventional throwaway syringe assembly proposed.

An object of the present invention is to provide a hub for a syringe,connecting structure of the hub, the syringe, a piston, a needleassembly unit, a connecting structure between the needle assembly unitand the syringe, a syringe assembly and a method of assembling thesyringe assembly, in a throwaway syringe assembly, with which safety ofthe operations can be maintained just after use till its disposal andits disposal operation does not require a long time, its assembly andoperation is easy, and which can be used for various purposes, takingthe above-mentioned circumstances into consideration.

SUMMARY OF THE INVENTION

Of the present invention, the 1st invention comprises a hub for asyringe assembly, said syringe assembly having a syringe body, such asthe syringe body 2, slidably attached a piston, such as the piston 39,thereto, said syringe body having a hub insertion hole, such as the hubinsertion hole 4b, cylindrically formed at a top thereof, said hub to beattachably and detachably attached to said hub insertion hole, said hubcomprising:

a cylindrical hub body, such as the hub body 15, through which said hubcan be inserted into said hub insertion hole and can be pulled out ofsaid hub insertion hole in said syringe body;

a held portion, such as the chamfer portion 16b, the held groove 61, orthe held rib 63, provided with said hub body so as to engage with saidhub insertion hole;

a needle insertion hole, such as the needle insertion hole 21, capableof inserting a needle, such as the needle 36, therein provided at oneend, such as the end face 20a, of said hub body in a direction of anaxis center, such as in the direction of the axis center P1, of said hubbody;

a flow hole, such as the flow hole 27, provided with said hub body suchthat said needle insertion hole and an inside of said syringe body canbe communicated with each other in said direction of said axis center;

a hub side engagement means, such as the piston engagement hole 29,provided at the other end, such as the end face 16a, of said hub body soas to engage with said piston; and

a seal taper, such as the seal taper 17 (the form of the seal taper maybe a plurality of fine rough portions annularly formed with the axiscenter P1 as its center, as well as a smooth face as shown in FIG. 5.),annularly provided with said hub body so as to abut on and contact withan inside face of said hub insertion hole such that its outside diameteris made narrower for said one end side of said hub body.

With this invention, the hub and the hub insertion hole are contactedwith each other through the seal taper and the held portion, and it iseasy to attach and detach the hub to and from the hub insertion hole. Inaddition, a predetermined seal efficiency and a predetermined holdingefficiency can be exercised between the hub and the hub insertion hole.The operation of disposing the hub in case of assembly and the operationof pulling the needle into the syringe assembly after use can besmoothly and easily executed.

Of the present invention the 2nd invention comprises a structure ofconnecting a hub in which a hub for a syringe assembly is attachably anddetachably connected with a syringe, such as the syringe 100, having asyringe body, such as the syringe body 2, formed a hub insertion hole,such as the hub insertion hole 4b, at a top thereof, said structure ofconnecting said hub comprising:

said hub body of said hub as set forth in claim 1 attachably anddetachably inserted in said hub insertion hole so as to be inserted intosaid hub insertion hole and be pulled out of said hub insertion hole insaid syringe body;

an insertion taper, such as the insertion taper 9, annularly providedwith said hub insertion hole such that its inside diameter is madenarrower for said top side of said syringe body, and said seal taper ofsaid hub body being contacted with said insertion taper with sealcontact with a predetermined seal pressure, such as the seal pressureF1,; and

a holding portion, such as the rib for holding 11, or the holding groove62, provided with an inner peripheral face of said hub insertion hole,being capable of engage with said held portion of said hub body, so asto hold and release said hub body with a predetermined holding force,such as the holding force F2.

With this invention, in addition to the effects of the 1st invention,the hub and the inner peripheral face of the hub insertion hole arecontacted with each other through the seal taper and the insertiontaper, and the held portion and the holding portion. Then, it is easy toattach and detach the hub to and from the hub insertion hole, and it iseasy and effective to assemble the syringe assembly. Besides, since thedirection in which the hub is pulled is one in which the seal taper isseparated from the insertion taper when the needle used is pulled intothe syringe assembly, the hub can be pulled inside the syringe assemblywith a small pulling force making use of seal pressure. And, it ispossible to smoothly easily execute the operation of discarding thesyringe assembly used.

Of the present invention the 3rd invention comprises a syringe assembly,comprising:

a syringe and a hub having the connecting structure of the 2ndinvention;

a piston, such as the piston 39, provided with said syringe body,occupying an inside of said syringe body in a direction of an axis so asto be movable in said direction of said axis with respect to saidsyringe body;

a piston side engagement means, such as the hub engagement portion 46,capable of engaging with said hub side engagement means of said hubprovided with said piston, facing said hub side engagement means; and

a needle, such as the needle 36, provided in said needle insertion holeof said hub.

With this invention, in addition to the effects of the 2nd invention, itis possible to engage the hub with the piston side engagement means ofthe piston after use so as to pull them inside of the syringe togetherwith the needle. The needle used can be easily pulled into the syringeby only the operation of pressing and pulling the piston, the same asthe operation of an usual syringe assembly. Then, its operation is easyfor everyone and there is no danger of error operation, and high safetyis secured.

Of the present invention, the 4th invention comprises the syringeassembly of the 3rd invention, wherein said piston is comprised suchthat a piston body, such as the piston body 40, can be bent and takenbetween an operation portion, such as the outer press plate 42, and aliquid medicine press portion, such as the inner press plate 43.

With this invention, in addition to the effects of the 3rd invention,the piston is bent and taken, thereby the needle can remain inside thesyringe being held with the top end portion of the piston. Then it ismot operable from the outside. High safety is secured in case ofdisposal operation after that.

Of the present invention, the 5th invention comprises the syringeassembly of the 4th invention, wherein a piston stopper, such as theengagement rib 3b, is provided with said syringe body so as not to pullsaid liquid medicine press portion of said piston out of said syringebody.

With this invention, in addition to the effects of the 4th invention, itis possible to prevent an operator from hurting with the needle used byinadvertently pulling the piston out of the syringe body when the pistonis moved together with the needle. Therefore, high safety is secured.

Of the present invention, the 6th and the 7th inventions comprise thesyringe assembly of the 4th or the 5th invention, wherein a notch forbending and taking, such as the notch 41, is formed at said piston bodyof said piston.

With both inventions, in addition of the effects of the respectiveinventions, the operation of bending and taking of the piston can beeasily executed by making use of the notches.

Of the present invention, the 8th invention comprises the syringeassembly of the 7th invention, wherein said notch is formed so as toposition at an end portion, such as the opening end 3a, of said syringebody when said piston abuts on said piston stopper.

With this invention, in addition to the effects of the respectiveinventions, the piston is pulled till it abuts on the piston stopper,and after that, the piston can be immediately bent and taken by makinguse of its end portion, and the operation of storing and remaining theneedle in the syringe can be successively executed. Therefore, theoperations of injection and disposal can be effectively executed.

Of the present invention, the 9th invention comprises a method ofassembling the syringe assembly of the 3rd invention, said methodcomprising:

inserting said hub into said hub insertion hole from a side where saidpiston is inserted into said syringe body, such as the arrow B side;

disposing said hub in such a manner that said seal taper of said hub andsaid insertion taper of said hub insertion hole are contacted with eachother with seal contact and said held portion of said hub and saidholding portion of said hub insertion hole are engaged with each other;and

inserting said piston into said syringe.

With this invention, assembly inserting the hub from the pistoninsertion side can be executed.

Of the present invention, the 10th invention comprises a syringeassembly, comprising:

a cylindrical syringe, such as the syringe X100, formed a liquid holdingspace, such as the medium holding space 153, therein, such as the insidespace 102a,;

a hub, such as the hub 109, attachably and detachably inserted into saidsyringe;

a needle, such as the needle 121, provided at a side back facing saidliquid holding space of said hub so as to join;

a hub side engagement means, such as the piston engagement hole 115,provided with said hub such that an opening, such as the opening 117b,is formed at an end portion of said hub, such as the end portion 110b,facing said liquid holding space of said syringe, such that acommunicating space, such as the piston engagement hole 115 and the flowhole 113, communicating with a liquid flow hole, such as the medium flowhole 121a, of said needle is formed;

a piston, such as the piston 123, occupying an inside of said syringe ina direction of an axis provided with said syringe, being movable in saiddirection of said axis, such as the directions as shown by the arrows XAand XB, with respect to said syringe;

a piston side engagement means, such as the hub engagement portion 131,provided with said piston, facing said hub side engagement means of saidhub, so as to be inserted into and engaged with said hub side engagementmeans; and

a first bypass means, such as the groove 132 and the bypass hole 139,communicating said communicating space and said liquid holding spacewith each other when said piston side engagement means is abutted onsaid hub, provided with said piston side engagement means.

With this invention, when the hub side engagement means and the pistonside engagement means are engaged with each other at the time of theoperation of storing the needle of the syringe assembly used, the liquidmedicine remaining in the liquid holding space and the like areoppressed between the hub and the piston. However, the liquid medicinein which pressure rises by the oppression adequately escapes on theliquid flow hole side of the needle through the first bypass means bydifferential pressure, and then pressure rise of the liquid medicineremaining in the liquid holding space is extremely low restricted, and aresistance by the liquid medicine in which pressure rises does notalmost acts on the piston. Then, the operation of the piston is easywithout a big force.

Of the present invention, the 11th invention comprises the syringeassembly of the 10th invention, wherein said first bypass means is agroove formed along a surface of said piston side engagement means.

With this invention, in addition to the effects of the 10th invention,forming the first bypass means at the piston side engagement meansbecomes to be easy.

Of the present invention, the 12th invention comprises the syringeassembly of the 10th invention, wherein said first bypass means is ahole formed at said piston side engagement means.

With this invention, in addition to the effects of the 10th invention,there is no contact between the first bypass means and the hub when thepiston side engagement means and the hub are abutted on each other.Then, the operation of the piston is certainly and easily executed sincethe first bypass means is not closed.

Of the present invention, the 13th invention comprises a syringeassembly, comprising:

a cylindrical syringe, such as the syringe X100, formed a liquid holdingspace, such as the medium holding space 153, therein, such as the insidespace 102a;

a hub, such as the hub 109, attachably and detachably inserted into saidsyringe;

a needle, such as the needle 121, provided on a side back facing saidliquid holding space of said hub so as to join;

a hub side engagement means, such as the piston engagement hole 115,provided with said hub such that an opening, such as the opening 117b,is formed at an end portion of said hub, such as the end portion 110b,facing said liquid holding space of said syringe, such that acommunicating space, such as the piston engagement hole 115 and the flowhole 113, communicating with a liquid flow hole, such as the medium flowhole 121a, of said needle is formed;

a second bypass means, such as the hub bypass groove 140 and the hubbypass hole 141, communicating said liquid holding space and saidcommunicating space with each other, provided with said hub;

a piston, such as the piston 123, occupying an inside of said syringe ina direction of an axis, such as the directions as shown by the arrows XAand XB, provided with said syringe, being movable in said direction ofsaid axis with respect to said syringe; and

a piston side engagement means, such as the hub engagement portion 131,provided with said piston, facing said hub side engagement means of saidhub, so as to be inserted into and engaged with said hub side engagementmeans.

With this invention, when the hub side engagement means and the pistonside engagement means are engaged with each other at the time of theoperation of storing the needle of the syringe assembly used, the liquidmedicine remaining in the liquid holding space and the like areoppressed between the hub and the piston. However, the liquid medicinein which pressure rises by the oppression adequately escapes on theliquid flow hole side of the needle through the second bypass means bydifferential pressure, and then pressure rise of the liquid medicineremaining in the liquid holding space is extremely low restricted, and aresistance by the liquid medicine in which pressure rises does notalmost act on the piston. Then, the operation of the piston is easywithout a big force.

Of the present invention, the 14th invention comprises the syringeassembly of the 13th invention, wherein said second bypass means is agroove formed along a surface of said hub side engagement means.

With this invention, in addition to the effects of the 13th invention,forming the second bypass means at the hub becomes to be easy.

Of the present invention, the 15th invention comprises the syringeassembly of the 13th invention, wherein said second bypass means is ahole formed at said hub.

With this invention, in addition to the effects of the 13th invention,there is no contact between the second bypass means and the piston sideengagement means when the piston side engagement means and the hub areabutted on each other. Then, the operation of the piston is certainlyand easily executed since the second bypass means is not closed.

Of the present invention, the 16th invention comprises the piston to beused for the syringe assembly of the 10th invention, comprising:

said piston having a piston body, such as the piston body 125,;

a press portion, such as the inner press plate 129, the packing support130, and the packing 133, provided with a top end side of said pistonbody, capable of occupying an inside of said syringe in a direction ofan axis, being slidable and movable inside said syringe in saiddirection of said axis;

a piston side engagement means provided with said top end side of saidpress portion, capable of being inserted into and engaged with said hubside engagement means; and

a first bypass means, such as the groove 132, the bypass hole 139,communicating said communicating space and said liquid holding spacewith each other when said piston side engagement means is abutted onsaid hub, provided with said piston side engagement means.

With this invention, in addition to the effects of the 10th invention,since the first bypass means is formed on the piston side, various kindsof hubs can be used according to a situation.

Of the present invention, the 17th invention comprises the piston of the16th invention, wherein said first bypass means is a groove formed alonga surface of said piston side engagement means.

In addition to the effects of the 16th invention, this invention has theeffects similar to ones of the 11th invention.

Of the present invention, the 18th invention comprises the piston of the16th invention, wherein said first bypass means is a hole formed at saidpiston side engagement means.

In addition to the effects of the 16th invention, this invention has theeffects similar to ones of the 12th invention.

Of the present invention, the 19th invention comprises a hub, such asthe hub 109, for a syringe assembly, to be inserted into a syringe, suchas the syringe X100, comprising:

said hub having a hub body, such as the hub body 190, capable ofattachably and detachably inserted into said syringe;

a needle insertion portion, such as the needle insertion hole 112,capable of inserting a needle, such as the needle 121, therein providedwith one end, such as the end portion 111a, of said hub body in adirection of an axis center of said hub body, such as the directions asshown by the arrows XA and XB;

a hub side engagement means, such as the piston engagement hole 115,provided with said hub body such that an opening, such as the opening117b, is formed at the other end, such as the end portion 110b, of saidhub body, such that a communicating space, such as the piston engagementhole 115 and the flow hole 113, communicating with said needle insertionportion is formed; and

a second bypass means, such as the hub bypass groove 140 and the hubbypass hole 141, communicating a liquid holding space, such as themedium holding space 153, inside said syringe and said communicatingspace with each other when said hub body is inserted into said syringe,formed at said hub body.

This invention has the effects similar to ones of the 13th invention.

Of the present invention, the 20th invention comprises the hub of the19th invention, wherein said second bypass means is a groove formedalong a surface of said hub side engagement means.

This invention has the effects similar to ones of the 14th invention.

Of the present invention, the 21st invention comprises the hub of the19th invention, wherein said second bypass means is a hole formed atsaid hub body.

This invention has the effects similar to ones of the 15th invention.

Of the present invention, the 22nd invention comprises a syringeassembly, comprising:

a cylindrical portion, such as the main cylindrical portion 203;

a cylindrical hub insertion portion, such as the hub insertion portion204, having an inside diameter smaller than one of said cylindricalportion provided with a top end side of said cylindrical portion suchthat a communicating portion, such as the taper 206, is formed betweensaid cylindrical portion and said hub insertion portion;

a hub, such as the hub 209, attachably and detachably inserted into saidhub insertion portion;

a needle, such as the needle 221, provided on a side back facing saidcylindrical portion of said hub so as to join;

a hub side engagement means, such as the piston engagement hole 215,provided on a side of said hub facing said cylindrical portion;

a piston body, such as the piston body 225, provided with saidcylindrical portion in such a manner that said piston body is insertedinto inside of said cylindrical portion;

a piston side engagement means, such as the hub engagement portion 231,provided with said piston body, facing said hub side engagement means ofsaid hub, capable of inserted into and engaged with said hub sideengagement means;

an occupying means, such as the packing 233, made of elastic material,provided with said piston body, occupying inside of said cylindricalportion in a direction of an axis, such as the directions as shown bythe arrows YA and YB, being slidable and movable together with saidpiston body in said direction of said axis with respect to saidcylindrical portion;

an engagement portion, such as the end portion 235d and the engagementprojection 255, capable of abutting on said communicating portion bymovement of said occupying means in said direction of said axis,provided with said occupying means; and

a pressing portion, such as the surface 235e, provided with saidoccupying means such that a gap space, such as the remaining space 251,can be formed between said pressing portion and said communicatingportion when said engagement portion and said communicating portion areabutted on each other.

With this invention, when the piston body is pressed on the hub sidefrom the injection end position so as to further feed the piston sideengagement means to the hub side in the operation of storing the needle,the occupying means receives a reaction from the communicating portionabutting in the portion near the engagement portion so as to becompressed in the direction of the axis. Besides, the pressing portionis pulled out on the hub side, narrowing the gap space, that is,approaching the communicating portion. That is, the quantity ofoppression of the occupying means is reduced by the quantity which thepressing portion is pulled out on the hub side in the gap space, andthen the feeding of the piston side engagement means can be executedwith extremely small force. Therefore, the operation of storing theneedle is easily executed.

Of the present invention, the 23rd invention comprises the piston, suchas the piston 233, to be used for the syringe assembly of the 22ndinvention, comprising:

said piston having a piston body, such as the piston body 225;

a piston side engagement means, such as the hub engagement portion 231,provided with a top end side of said piston body so as to be insertedinto and engaged with said hub side engagement means;

an occupying means, such as the packing 233, made of elastic material,provided with said piston body, capable of occupying inside of saidcylindrical portion, such as the main cylindrical portion 203, in adirection of an axis, such as the directions as shown by the arrows YAand YB, being slidable and movable together with said piston body insaid direction of said axis with respect to said cylindrical portion;

an engagement portion, such as the end portion 235d and the engagementprojection 255, capable of abutting on said communicating portion, suchas the taper 206, by movement of said occupying means in said directionof said axis with respect to said cylindrical portion, provided withsaid occupying means; and

a pressing portion, such as the surface 235e, provided with saidoccupying means such that a gap space, such as the remaining space 251,can be formed between said pressing portion and said communicatingportion when said engagement portion and said communicating portion areabutted on each other.

This invention has the effects similar to ones of the 22nd invention byapplying the piston to the syringe assembly of the 22nd invention.

Of the present invention, the 24th invention comprises a syringeassembly comprising:

a cylindrical syringe, such as the syringe Y100, formed a liquid holdingspace, such as the medium holding space 253, therein;

a hub, such as the hub 209, attachably and detachably inserted into saidsyringe;

a needle, such as the needle 221, provided on a side back facing saidliquid holding space of said hub so as to join;

a hub side engagement means, such as the piston engagement hole 215,provided on a side facing said liquid holding space of said hub;

a piston body, such as the piston body 225, provided with said syringein such a manner that said piston body is inserted inside of saidsyringe;

a piston side engagement means, such as the hub engagement portion 231,provided with said piston body, facing said hub side engagement means ofsaid hub, so as to be inserted into and engaged with said hub sideengagement means;

an occupying member, such as the packing 233, made of elastic materialoccupying inside said syringe in a direction of an axis, such as thedirections as shown by the arrows YA and YB, being movable together withsaid piston body in said direction of said axis with respect to saidsyringe, provided with said piston body, and

a deformation accelerating space, such as the clearance space 235f,formed inside of said occupying member.

With this invention, when the occupying member is elastically oppressedin the operation of storing the needle so as to engage the piston andthe hub are engaged with each other, the deformation accelerating spaceinside the occupying member can be oppressed with a smaller force incomparison with the oppression of elastic material, and the quantity ofelastic oppression in the occupying member is reduced by the quantity ofthe deformation accelerating space. Therefore, the piston and the hubcan be engaged with each other with an extremely small force, and then,the operation of storing the needle can be easily executed.

Of the present invention, the 25th invention comprises the syringeassembly of the 24th invention, wherein said deformation acceleratingspace is hollow.

With this invention, in addition to the effects of the 24th invention,since the deformation accelerating space can be oppressed extremelyeasily, the engagement between the piston and the hub further becomes tobe easy.

Of the present invention, the 26th invention comprises the syringeassembly of the 24th invention, wherein said deformation acceleratingspace is filled with soft material being softer than said occupyingmember.

With this invention, in addition to the effects of the 24th invention,since entering injection medium or air into the deformation acceleratingspace is saved, the holding quantity of the injection medium in theliquid holding space in the syringe or the quantity of air remaining inthe liquid holding space is correctly grasped and credibility isincreased.

Of the present invention, the 27th invention comprises the piston, suchas the piston 223, to be used for the syringe assembly of the 24thinvention:

said piston having a piston body, such as the piston body 225;

a piston side engagement means, such as the hub engagement portion 231,provided with a top end side of said piston body so as to be insertedinto and engaged with said hub side engagement means;

an occupying member, such as the packing 233, made of elastic material,provided with said piston body, capable of occupying inside of saidsyringe in a direction of an axis, such as the directions as shown bythe arrows YA and YB, being movable together with said piston body insaid direction of said axis with respect to said syringe; and

a deformation accelerating space, such as the clearance space 235f,formed inside said occupying member.

This invention has the effects similar to ones of the 24th invention byapplying the piston of the 27th invention to the syringe assembly.

Of the present invention, the 28th invention comprises the piston of the27th invention, wherein said deformation accelerating space is hollow.

This invention has the effects similar to ones of the 25th invention byapplying the piston of the 28th invention to the syringe assembly.

Of the present invention, the 29th invention comprises the piston of the27th invention, said deformation accelerating space is filled with softmaterial being softer than said occupying member.

This invention has the effects similar to ones of the 26th invention byapplying the piston of the 29th invention to the syringe assembly.

Of the present invention, the 30th invention comprises an occupyingmember for a syringe assembly comprising:

a main body, such as the packing body 235, made of elastic material;

a sliding face for syringe, such as the sliding face 235g, formed at aperiphery of said main body;

a liquid pressing face, such as the surface 235e, formed at one end ofsaid main body;

a supporting face, such as the supporting face 235h, formed at the otherend of said main body;

a piston engagement insertion space, such as the engagement hole 235a,provided with said main body; and

a deformation accelerating space, such as the clearance space 235f,formed between said piston engagement insertion space and said slidingface for syringe.

This invention has the effects similar to ones of the 27th invention byapplying the occupying member of the 30th invention to the piston.

Of the present invention, the 31st invention comprises the occupyingmember of the 30th invention, wherein said deformation acceleratingspace is hollow.

This invention has the effects similar to ones of the 28th invention byapplying the occupying member of the 31st invention to the piston.

Of the present invention, the 32nd invention comprises the occupyingmember of the 30th invention, said deformation accelerating space isfilled with soft material being softer than said main body.

This invention has the effects similar to ones of the 29th invention byapplying the occupying member of the 32nd invention to the piston.

Of the present invention, the 33rd invention comprises a needle assemblyunit comprising:

a hub body, such as the hub body 310, cylindrically formed;

an abutting end portion, such as the end face 310a, formed on one endside of said hub body;

an engagement holding portion, such as the engagement holding pillarportion 311, provided with said abutting end portion side of said hubbody, having an outside diameter, such as the outside diameter ZL2,smaller than one, such as the outside diameter ZL1 or ZL1', of said hubbody;

a needle, such as the needle 321, connected with said engagement holdingportion;

an engagement means for piston, such as the piston engagement hole 315,provided on an opposite side of said one end side of said hub body;

an engagement means for syringe, such as the hub stop groove 310c,annularly formed on an outer peripheral face side, such as the outerperipheral face 310f, of said hub body;

a reaction fixed member, such as the hub fixed member 361, formed a hubengagement hole, such as the hub engagement hole 362, provided with saidengagement holding portion so as to engage such that said engagementholding portion is inserted into said hub engagement hole so as to beinserted into and pulled out of; and

a fixed means for syringe, such as the syringe engagement projection363, formed at said reaction fixed member.

When the needle assembly unit according to this invention is connectedwith the syringe for the syringe assembly, the reaction fixed member ofthe needle assembly unit is fixed by and engaged with the syringethrough the syringe fixed member, and therefore, the abutting endportion side of the hub body can be indirectly supported by the syringethrough the reaction fixed means. Then, no means for directly supportingthe hub body so as not to slip the hub body out of the top end sidethereof to the outside may be provided on the syringe for connectingwith the needle assembly unit. And, the syringe having no means fordirectly supporting the hub body is used, thereby the hub body can beeasily inserted from the top end side of the syringe since no resistanceis received at the time of insertion. Accordingly, when the needleassembly unit according to this invention is used, the hub bodyconnected the needle can be easily connected with the syringe at thesite of treatment. Then, a plurality of kinds of needle assembly unitsand a plurality of kinds of syringes which are respectively not yetconnected with each other are prepared at the site of treatment, andthen, according to use, such as treatment, appropriate needle assemblyunit and the syringe to be used are selected from a plurality of kindsof the needle assembly units and a plurality of kinds of the syringes soas to connect both with each other just before injection action. As aresult, the syringe assembly can be used for various purposes.

Of the present invention, the 34th invention comprises a syringecomprising:

a syringe body, such as the syringe body 302, in the shape of acylinder;

a hub insertion portion, such as the hub insertion portion 307,cylindrically formed on a top end side of said syringe body through ahub introducing opening, such as the opening end 307g;

an engagement means for reaction fixed member, such as the hub fixedmember engagement groove 307c, formed on an outer peripheral face side,such as the outer peripheral face 307f, of said hub insertion portion;and

an engagement means for hub, such as the hub stop rib 307d, annularlyformed on an inner peripheral face side, such as the inner peripheralface 307a, of said hub insertion portion.

The reaction fixed member is engaged with and fixed by the syringeaccording to this invention through the reaction fixed member engagementmeans. When the hub body for the syringe assembly is inserted into thesyringe, the hub body can be indirectly supported by the syringe sidethrough the reaction fixed member so as not to slip the hub body out ofthe top end side of the syringe to outside. Then, no means for directlysupporting the hub body so as not to slip the hub body out of the topend side of the syringe to the outside may be provided on the syringe.That is, the hub body can be easily inserted from the top end side ofthe syringe since no resistance is received at the time of insertion.Accordingly, when the syringe according to this invention is used, thehub body connected the needle can be easily connected with the syringeat the site of treatment. Then, a plurality of kinds of needlesconnected with the hub body, engaging with the reaction fixed member andthe syringe are prepared in such a state that both are not yet connectedwith each other at the site of treatment, and then, according to use,such as treatment, a needle is selected from a plurality of kinds ofneedles for a syringe (or, a syringe is selected from a plurality ofkinds of syringes for a needle) so as to connect with each other justbefore the injection action. As a result, the syringe assembly can beused for various purposes.

Of the present invention, the 35th invention comprises a connectingstructure between the needle assembly unit of the 33rd invention and thesyringe of the 34th invention, comprising:

said hub body inserted inside of said hub insertion portion such thatsaid abutting end portion side of said hub body is back faced to saidsyringe body, such that said engagement means for syringe of said hubbody and said engagement means for hub of said hub insertion portion arefree to be engaged with and disengaged from each other; and

said reaction fixed member installed on an outer peripheral face side ofsaid hub insertion portion such that said engagement means for reactionfixed member of said hub insertion portion and said fixed means forsyringe of said reaction fixed member are engaged with each other.

The needle assembly unit of the 33rd invention and the syringe of the34th invention can be easily connected with each other at the site oftreatment, forming the connecting structure according to this invention.Then, a plurality of kinds of needles connected with the hub body,engaging with the reaction fixed member and a plurality of kinds ofsyringes are prepared in such a state that both are not yet connectedwith each other at the site of treatment, and then, according to use,such as treatment, a needle is selected for a plurality of kinds ofsyringes or a plurality of kinds of needles are selected for a syringejust before the injection action so as to connect with each other. As aresult, the syringe assembly can be used for various purposes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a typical sectional view showing an example of a syringeassembly according to the present invention;

FIG. 2 is an enlarged sectional view in a portion near a hub of thesyringe assembly as shown in FIG. 1;

FIG. 3 is a view showing a routine of engaging the hub as shown in FIG.2 with the piston;

FIG. 4 is a view showing bending and taking of the piston in the syringeassembly as shown in FIG. 1;

FIG. 5 is a view showing an example of the hub in which a held portionis formed in the shape of a groove;

FIG. 6 is a view showing an example of a hub insertion hole in which aholding portion is formed in the shape of a groove and the hub in whichthe held portion is formed in the shape of a projection;

FIG. 7 is a typical sectional view showing an example of a syringeassembly according to the present invention;

FIG. 8 is a view showing the whole syringe assembly as shown in FIG. 7;

FIG. 9 is a view showing an insertion portion of a hub engagementportion of the syringe assembly as shown in FIG. 7 seen from the arrowXB direction of the figure;

FIG. 10 is a view showing the hub insertion portion of the syringeassembly as shown in FIG. 7 seen from the arrow XB direction in thefigure;

FIG. 11 is a view showing bending and taking of the piston in thesyringe assembly as shown in FIG. 7;

FIG. 12 is a typical sectional view showing an example of the syringeassembly in which a seal rib is formed on the hub side and a seal grooveis formed on the hub insertion hole side, of the syringe assemblyaccording to the present invention;

FIG. 13 is a typical sectional view showing an example of the syringeassembly in which the seal rib is formed on the hub side and a hub sealportion of the hub insertion hole side corresponds with the innerperipheral face of the hub insertion hole, of the syringe assemblyaccording to the present invention;

FIG. 14 is a typical sectional view showing an example of the syringeassembly in which fold portions are formed on the hub side and the hubseal portion of the hub insertion hole side corresponds with the innerperipheral face of the hub insertion hole, of the syringe assemblyaccording to the present invention;

FIG. 15 is a typical sectional view showing an example of the syringeassembly in which a first bypass means is a bypass hole, of the syringeassembly according to the present invention;

FIG. 16 is a typical sectional view showing an example of the syringeassembly in which a second bypass means is a hub bypass groove, of thesyringe assembly according to the present invention;

FIG. 17 is a typical sectional view showing an example of the syringeassembly in which the second bypass means is the hub bypass hole, of thesyringe assembly according to the present invention;

FIG. 18 is a sectional view showing the hub and the portion near the topof the piston, of an example of the syringe assembly according to thepresent invention;

FIG. 19 is a typical sectional view showing the whole syringe assemblyas shown in FIG. 18;

FIG. 20 is a view showing a portion near a hub insertion portion of thesyringe assembly as shown in FIG. 19;

FIG. 21 is a view showing the hub insertion portion of the syringeassembly as shown in FIG. 19 seen from the arrow YB direction;

FIG. 22 is a view showing a routine of bending and taking the piston ofthe syringe assembly as shown in FIG. 19;

FIG. 23 is a sectional view showing an example of another syringeassembly according to the present invention;

FIG. 24 is the sectional view showing the hub and the portion near thetop of the piston, of an example of the syringe assembly according tothe present invention;

FIG. 25 is a typical sectional view showing the whole syringe assemblyas shown in FIG. 24;

FIG. 26 is a view showing an operation of bending and taking the pistonof the syringe assembly as shown in FIG. 25;

FIG. 27 is a sectional view showing connecting portion of an example ofa needle assembly unit according to the present invention and an exampleof a syringe according to the present invention;

FIG. 28 is a sectional view showing a whole syringe assembly to whichthe needle assembly unit and the syringe as shown in FIG. 27 areapplied;

FIG. 29 is a view showing a state in which a cap for storing isinstalled on the needle assembly unit as shown in FIG. 27; and

FIG. 30 is a view showing a way of bending and taking the piston in thesyringe assembly as shown in FIG. 28.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Embodiments of the present invention will now be described hereinafterwith respect to the accompanying drawings.

A syringe assembly 1 according to the present invention has a syringe100 made of resin, as shown in FIG. 1. A syringe body 2 is provided withthe syringe 100 (FIG. 1 is a typical cross section of the syringeassembly 1, but a side is shown in a part of a piston 39, describedhereinafter, not the section, for convenience.). A main cylindricalportion 3, cylindrically formed, is provided with the syringe body 2. Adirection of an axis center of the main cylindrical portion 3, that is,the reciprocating directions parallel to an axis center P1 are an arrowA direction in the figure (or the left direction of the paper of FIG.1.) and an arrow B direction (or the right direction of the paper ofFIG. 1).

On the outer periphery side of the main cylindrical portion 3, a syringesupport 5, being in the shape of a plate, is provided near an openingend 3a of the arrow B side of the main cylindrical portion 3 (the rightside of the paper of FIG. 1), in such a manner as forming a flange ofthe main cylindrical portion 3. On an inner peripheral face 3c side ofthe main cylindrical portion 3, an engagement rib 3b, projecting in thedirection for the axis center P1 of the main cylindrical portion 3, thatis, the direction as shown by an arrow D of the figure, is annularlyformed near the opening end 3a along the inner peripheral face 3c.

On the arrow A side of the main cylindrical portion 3 (the left side ofthe paper of FIG. 1) a taper 6 in the shape of a funnel is formedunitedly connecting with the main cylindrical portion 3. The insidediameter in the section perpendicular to the directions as shown by thearrows A and B of the taper 6 (that is, the circular section) is madenarrower for the direction as shown by the arrow A.

The inside of the main cylindrical portion 3 and the inside of the taper6 communicate with each other in the directions as shown by the arrows Aand B, and the space which consists of both insides combined is aninside space 2a of the syringe body 2.

On the side of the arrow A of the taper 6, that is, on the side of thetop of the syringe body 2, as shown in FIGS. 1 and 2, a cylindrical hubinsertion portion 4 is formed unitedly connecting with the taper 6, andthe hub insertion portion 4 has a first small cylindrical portion 7. Onthis occasion, the first small cylindrical portion 7 is formed unitedlyconnecting with the taper 6, and the hub insertion portion 4 is formedunitedly connecting with the taper 6 in the first small cylindricalportion 7.

On the arrow A side of the first small cylindrical portion 7, aninsertion taper 9 in the shape of a funnel is formed unitedly connectingwith the first small cylindrical portion 7. The inside diameter in thesection perpendicular to the directions as shown by the arrows A and Bof the insertion taper 9 (that is, the circular section) is madenarrower for the direction as shown by the arrow A.

On the arrow A side of the insertion taper 9, a second small cylindricalportion 10 in the shape of a cylinder is formed, and the second smallcylindrical portion 10 is formed unitedly connected with the insertiontaper 9.

The first small cylindrical portion 7, the insertion taper 9 and thesecond small cylindrical portion 10 are respectively formed coaxial withthe main cylindrical portion 3. An inside diameter L1 of the first smallcylindrical portion 7 is smaller than one of the main cylindricalportion 3, and an inside diameter L2 of the second small cylindricalportion 10 is smaller than the inside diameter L1 of the first smallcylindrical portion 7 (However, the inside diameter L1 of the firstsmall cylindrical portion 7 is one in portions excluding a rib forholding 11, as described hereinafter.).

On the side of an inner peripheral face 7a of the first smallcylindrical portion 7, the side of an inner peripheral face 9a of theinsertion taper 9, and the side of an inner peripheral face 10a of thesecond small cylindrical portion 10, a hub insertion hole 4b is formedcommunicating in the directions as shown by the arrows A and B. The ribfor holding 11 is formed projecting for the axis center P1 near the endportion of the arrow B side of the hub insertion hole 4b, that is, nearthe boundary portion between the first small cylindrical portion 7 andthe taper 6. The rib for holding 11 is formed along a circumferencewhich center is the axis center P1, that is, annularly formed along theinner peripheral face 7a of the first small cylindrical portion 7.

An end wall 12, being in the shape of a circular plate, is formed on thearrow A side of the second small cylindrical portion 10 such that theoutside diameter of the end wall 12 is equal to one of the second smallcylindrical portion 10 and both front and back wall faces thereof areperpendicular to the directions as shown by the arrows A and B. The endwall 12 is provided matching with the second small cylindrical portion10 and being united therewith. A circular hole 12a, which center is theaxis center P1, is provided with the end wall 12 penetrating both frontand back wall faces of the end wall 12 in the directions as shown by thearrows A and B.

As described before, the hub insertion portion 4 is comprised of thefirst small cylindrical portion 7, the insertion taper 9, the secondsmall cylindrical portion 10 and the end wall 12. The syringe 100 iscomprised such that the syringe body 2 and the syringe support 5 areunitedly formed. The syringe body 2 is comprised such that the maincylindrical portion 3, the taper 6 and the hub insertion portion 4 areunitedly formed.

On the other hand, as shown in FIG. 2, a hub 13 is inserted into the hubinsertion hole 4b of the hub insertion portion 4, and the hub 13 has ahub body 15. The first pillar portion 16 in the shape of a cylinder,which longitudinal direction is parallel to the directions as shown bythe arrows A and B and which axis center is the axis center P1, isprovided with the hub body 15. On the arrow A side of the first pillarportion 16, a seal taper 17, which axis center is the axis center P1, istaperingly formed, unitedly connecting with the first pillar portion 16.The section perpendicular to the directions as shown by the arrows A andB of the seal taper 17 (that is, the circular section) is made narrowerfor the direction as shown by the arrow A. On the arrow A side of theseal taper 17, the second pillar portion 19 in the shape of a cylinder,which axis center is the axis center P1, is formed. The second pillarportion 19 is formed unitedly connecting with the seal taper 17.

An end face 16a is formed at the end portion of the arrow B side of thefirst pillar portion 16 (the right side of the paper of FIG. 2),perpendicular to the directions as shown by the arrows A and B. Chamferportions 16b are taperingly formed at the corner portions of theperipheral side in the end face 16a. An end face 19a is formed at theend portion of the arrow A side of the second pillar portion 19 (theleft side of the paper of FIG. 2), perpendicular to the directions asshown by the arrows A and B. Chamfer portions 19b are taperingly formedat the corner portions of the peripheral side in the end face 19a.

On the end face 19a side of the second pillar portion 19, a third pillarportion 20, projecting and extending in the direction as shown by thearrow B, is provided united with the second pillar portion 19, andcoaxial therewith.

As described before, the hub body 15 is comprised of the first pillarportion 16, the seal taper 17, the second pillar portion 19, and thethird pillar portion 20. The hub body 15 is inserted into the hubinsertion hole 4b of the hub insertion portion 4 in such a manner thatthe first pillar portion 16 is inserted in the inner peripheral face 7aside of the first small cylindrical portion 7, the seal taper 17 isinserted in the inner peripheral face 9a side of the insertion taper 9,the second pillar portion 19 is inserted in the inner peripheral face10a side of the second small cylindrical portion 10, and the thirdpillar portion 20 is inserted into the hole 12a of the end wall 12penetrating the hole 12a.

The hub body 15 is inserted such that the seal taper 17 matches andclosely contacts with the inner peripheral face 9a of the insertiontaper 9, and the chamfer portion 16b of the first pillar portion 16matches and closely contacts with a side face 11a of the arrow A side ofthe rib for holding 11 (that is, the left side of the paper of FIG. 2.).

On this occasion, the seal taper 17 receives a seal pressure F1 from theinsertion taper 9 in a direction perpendicular to a contact face, thatis, the direction perpendicular to the inner peripheral face 9a, and inthe direction as shown by the arrow E in the figure for the axis centerP1. The chamfer portion 16b receives a holding force F2 from the rib forholding 11 in a direction perpendicular to a contact face, that is, thedirection perpendicular to the side face 11a of the rib for holding 11,and in the direction as shown by the arrow G in the figure, inclined tothe axis center P1.

That is, in such a state that the hub 13 is inserted into the hubinsertion hole 4b, the first small cylindrical portion 7 is elasticallydeformed slightly extending in the directions as shown by the arrows Aand B, and by its restoring force, the seal pressure F1 and the holdingforce F2, above-mentioned, are supplied. The seal pressure F1 and theholding force F2 match with each other through the hub 13 such that theseal pressures F1 and F1, the holding forces F2 and F2, or the sealpressure F1 and the holding force F2 match with each other in thedirections as shown by the arrows C and D, or in the directions as shownby the arrows A and B, thereby the hub 13 is fixed.

The outside diameter L1' of the first pillar portion 16 is smaller thanthe inside diameter L1 of the first small cylindrical portion 7 in theportion existing no rib for holding 11, and the outside diameter L2' ofthe second pillar portion 19 is smaller than the inside diameter L2 ofthe second small cylindrical portion 10. Therefore, a first gap space 56is formed between an outer peripheral face 16e of the first pillarportion 16 and the inner peripheral face 7a of the first smallcylindrical portion 7. A second gap space 57 is formed between an outerperipheral face 19c of the second pillar portion 19 and the innerperipheral face 10a of the second small cylindrical portion 10.

The outside diameter of the third pillar portion 20 is slightly smallerthan (or the same as) the inside diameter of the hole 12a formed at theend wall 12. A wall face 12b of the arrow B side of the end wall 12(that is, the right side of the paper of FIG. 2) and the end face 19a ofthe second pillar portion 19 almost contact with each other, but one ofboth do not operate pressing force to the other. The hub body 15 isinserted as described before.

A needle insertion hole 21 is provided with the hub 13, as shown in FIG.2. The needle insertion hole 21 is comprised of a first taper hole 22, afirst pillar hole 23, a second taper hole 25 and a second pillar hole26.

The first taper hole 22 forms an opening 22a in the shape of a circular,which center is the axis center P1, at an end face 20a of the arrow Aside of the third pillar portion 20 of the hub 13 (the left side of thepaper of FIG. 2), and is formed for the direction as shown by the arrowB from the end face 20a. The diameter of the section perpendicular tothe directions as shown by the arrows A and B of the first taper hole 22(that is, the circular section, which center is the axis center P1) ismade narrower for the direction as shown by the arrow B.

On the arrow B side of the first taper hole 22, the first pillar hole 23in the shape of a cylinder, which center is the axis center P1, isprovided connecting with the first taper hole 22. On the arrow B side ofthe first pillar hole 23, the second taper hole 25 is provided in thedirection as shown by the arrow B, connecting with the first pillar hole23. The diameter of the section perpendicular to the directions as shownby the arrows A and B of the second taper hole 25 (that is, the circularsection which center is the axis center P1) is made narrower for thedirection as shown by the arrow B.

On the arrow B side of the second taper hole 25, the second pillar hole26 in the shape of a cylinder, which center is the axis center P1, isprovided, connecting with the second taper hole 25. An end portion 26aof the arrow B side of the second pillar hole 26 reaches the inside ofthe first pillar portion 16. The end portion 26a of the second pillarhole 26 contacts with a wall face 16c perpendicular to the directions asshown by the arrows A and B.

On the other hand, a flow hole 27 is provided with the first pillarportion 16 of the hub 13, adjacent to the arrow B side of the secondpillar hole 26 of the needle insertion hole 21 (the right side of thepaper of FIG. 2). The flow hole 27, which center is the axis center P1,having the diameter smaller than one of the second pillar hole 26, isprovided in the shape of a cylinder. The flow hole 27 communicates withthe second pillar hole 26 of the needle insertion hole 21, forming acircular opening 27a at the wall face 16c of the first pillar portion16.

A piston engagement hole 29 is provided with the first pillar portion 16of the hub 13, adjacent to the arrow B side of the flow hole 27 (theright side of the paper of FIG. 2). The piston engagement hole 29 iscomprised of the first taper hole 30, the pillar hole 31, the secondtaper hole 32 and the third taper hole 33.

The first taper hole 30 is provided in the first pillar portion 16,adjacent to the arrow B side of the flow hole 27 (the right side of thepaper of FIG. 2). The section perpendicular to the directions as shownby the arrows A and B of the first taper hole 30 is a circular section,which center is the axis center P1. The diameter of the section of thefirst taper hole 30 is made wider for the direction as shown by thearrow B. The diameter of a circular end portion 30a of the arrow A sideof the first taper hole 30 is bigger than one of the flow hole 27.Therefore, the end portion 30a contacts with a wall face 16dperpendicular to the directions as shown by the arrows A and B. At thewall face 16d, a circular opening 27b is formed by provision of the flowhole 27. The first taper hole 30 and the flow hole 27 communicate witheach other through the opening 27b.

On the arrow B side of the first taper hole 30, the pillar hole 31 inthe shape of a cylinder, which center is the axis center P1, is providedconnecting with the first taper hole 30. On the arrow B side of thepillar hole 31, the second taper hole 32, which diameter of the sectionperpendicular to the directions as shown by the arrows A and B (that is,the circular section which center is the axis center P1) is madenarrower for the direction as shown by the arrow B, is provided in thedirection as shown by the arrow B, connecting with the pillar hole 31.On the arrow B side of the second taper hole 32, the third taper hole 33is provided in the direction as shown by the arrow B, connecting withthe second taper hole 32. The diameter of the section perpendicular tothe directions as shown by the arrows A and B of the third taper hole 33(that is, the circular section which center is an axis center P2) ismade wider for the direction as shown by the arrow B. Therefore, theportion sandwitched between a wall face 35b facing the second taper hole32 and a wall face 35c facing the third taper hole 33 forms a projection35a, projecting for the axis center P1 with a boundary portion 35between the second taper hole 32 and the third taper hole 33 of thefirst pillar portion 16 as an apex.

The arrow B side of the third taper hole 33 opens outside forming acircular opening 33a at the end face 16a of the first pillar portion 16.

On the other hand, a needle 36 is inserted into the needle insertionhole 21 of the hub 9, as shown in FIG. 1 or FIG. 2. The top of theneedle 36 positions at the outside of the syringe body 2, and the needle36 is inserted into the needle insertion hole 21 from the rear end side.The rear end of the needle 26 abuts on the wall face 16c formed on thearrow B side of the needle insertion hole 21. A medium flow hole 36aprovided penetrating in the directions as shown by the arrows A and Bfrom the top to the rear of the needle 36 and the flow hole 27communicate with each other in the directions as shown by the arrows Aand B through the right end portion of FIG. 2 of the flow hole 36a.

An adhesive 37 is filled with in a space between the needle 36 and thehub 13 of the needle insertion hole 21 and is hardened.

As shown in FIG. 1, the piston 39 is provided with the syringe assembly1 (FIG. 1 is a typical cross section of the syringe assembly 1, but aside is shown in a piston body 40, an outer press plate 42 and an innerpress plate 43, described hereinafter, of the piston 39, not thesection, for convenience.).

The piston 39 has the bar-shaped piston body 40 extending in thedirections as shown by the arrows A and B. The piston body 40 iscomprised such that two congruent plate portions 40a, each which is aplate shaped rectangle especially long in the directions as shown by thearrows A and B, are unitedly cross provided with each other such thatthe sections thereof form the shape of a cross. The width perpendicularto the directions as shown by the arrows A and B of the plate face ofthe plate portion 40a is almost equal to the inside diameter at theengagement rib 3b of the main cylindrical portion 3, and the piston body40 is inserted into the main cylindrical portion 3 through the openingend 3a from the arrow A side of the piston body 40.

On each plate portion 40a of the piston body 40, notches 41 are formedfrom both side portions 40b, 40b of respective plate portions 40a, 40ato the direction of the axis center (that is, the axis center P1) of thepiston body 40 in the shape of a wedge near the direction by the arrowA. Four notches 41 are provided at the positions adjusted one another inthe directions as shown by the arrows A and B.

The outer press plate 42, which plate face is a circular plateperpendicular to the directions as shown by the arrows A and B, isprovided on the end portion side of the arrow B side of the piston body40, being united with the piston body 40, and coaxial with the pistonbody 40. The diameter of the outer press plate 42 is fully bigger thanthe inside diameter of the main cylindrical portion 3.

As shown in FIG. 1, the inner press plate 43, which plate face is acircular plate perpendicular to the directions as shown by the arrows Aand B, is provided on the end portion side of the arrow A side of thepiston body 40, being united with the piston body 40 and coaxial withthe piston body 40 (Therefore, the inner press plate 43 is positionedinside the main cylindrical portion 3.). The diameter of the inner pressplate 43 is almost equal to the inside diameter of the main cylindricalportion 3 (Therefore, the diameter of the inner press plate 43 is biggerthan the inside diameter at the engagement rib 3b of the maincylindrical portion 3.).

As shown in FIG. 1, a packing support 45 is provided with the innerpress plate 43 on the arrow A side of it. A pillar portion 45a in theshape of a circular cylinder, which extends in the directions as shownby the arrows A and B, is provided with the packing support 45, coaxialwith the inner press plate 43. The diameter of the pillar portion 45a issmaller than one of the inner press plate 43, and the pillar portion 45ais provided on the arrow A side of the inner press plate 43, beingunited with the inner press plate 43. A circular plate portion 45b,which plate face is a circular plate perpendicular to the directions asshown by the arrows A and B, is provided on the arrow A side of thepillar portion 45a, coaxial with the pillar portion 45a, united with thepillar portion 45a. The diameter of the circular plate portion 45b isbigger than one of the pillar portion 45a, and is smaller than one ofthe inner press plate 43.

A hub engagement portion 46 is provided on the arrow A side of thecircular plate portion 45b, and a pillar portion 46a in the shape of acircular cylinder, which extends in the directions as shown by thearrows A and B, is provided with the hub engagement portion 46, coaxialwith the circular plate portion 45b. The diameter of the pillar portion46a is smaller than one of the circular plate portion 45b. The pillarportion 46a is provided on the arrow A side of the circular plateportion 45b, being united with the circular plate portion 45b. Asemi-spherical insertion portion 46b, which diameter is bigger than oneof the pillar portion 46a is provided on the arrow A side of the pillarportion 46a, united with the pillar portion 46a, directing a sphericalsurface 46c to the arrow A side.

The diameter of the pillar portion 46a is almost equal to the insidediameter of the boundary portion 35 between the second taper hole 32 andthe third taper hole 33 of the piston engagement hole 29 provided at thehub 13, and the diameter of the insertion portion 46b is smaller thanthe inside diameter of the cylindrical hole 31 of the piston engagementhole 29.

On the other hand, a packing 47 made of flexible resin is supportinglyprovided with the packing support 45. The packing 47 is comprised of apillar portion 49, which extends in the directions as shown by thearrows A and B, and a taper 50, connecting the arrow A side of thepillar portion 49, being united with the pillar portion 49. The outsidediameter of the taper 50 is made narrower for the direction as shown bythe arrow A. The form of the taper 50 allow the taper 50 to be insertedinto the inside of the taper 6 of the syringe body 2 in a natural stateso as to adjust to the inside of the taper 6.

A first hole 51, which diameter is the same as one of the pillar portion45a of the packing support 45, and which length in the directions asshown by the arrows A and B is the same as one of the pillar portion45a, is provided with the packing 47 in the direction as shown by thearrow A from an end face 49a side of the arrow B side of the pillarportion 49, coaxial with the pillar portion 49. Furthermore, a secondhole 52, which diameter is the same as one of the circular plate portion45b of the packing support 45, and which length in the directions asshown by the arrows A and B is the same as one of the circular plateportion 45b, is provided with the packing 47, connecting with the arrowA side of the first hole 51, coaxial with the pillar portion 49. And, athird hole 53, which diameter is the same as the outside diameter of thesection perpendicular to the directions as shown by the arrows A and Bof the insertion portion 46b of the hub engagement portion 46, and whichlength in the directions as shown by the arrows A and B is the same asone of the pillar portion 46a of the hub engagement portion 46 isprovided with the packing 47, connecting with the arrow A side of thesecond hole 52, coaxial with the pillar portion 49. The third hole 53 isopen on the taper 50 side of the packing 47 to the direction as shown bythe arrow A.

In other words, the packing 47 is provided so as to engage with thepacking support 45 such that the pillar portion 46a of the hubengagement portion 46 penetrates the third hole 53, the circular plateportion 45b of the packing support 45 is inserted into the second hole52, and the pillar portion 45a of the packing support 45 penetrates thefirst hole 51.

In such a state that the taper 50 of the packing 47 is inserted andadjusted into the inside of the taper 6 of the syringe body 2 in anatural state, as shown in FIG. 3, the form of the packing 47 is set insuch a manner that the spherical surface 46c of the insertion portion46b of the hub engagement portion 46 of the arrow A side of the packingsupport 45 which is engaged with the packing 47 is in contact with thewall face 35c facing the third taper hole 33 of the piston engagementhole 29.

The diameter of the pillar portion 49 of the packing 47 is almost equalto one of the inner press plate 43. However, on the outer periphery sideof the pillar portion 49 of the packing 47, annular folds 55 are doubleformed, being arranged in the directions as shown by the arrows A and Balong the outer periphery of the pillar portion 49. Then, the pillarportion 49 and the fold 55 of the packing 47 are inserted into the maincylindrical portion 3 of the syringe body 2, reducing their sizes byelastic deformation in the direction for the axis center P1 (that is, inthe direction as shown by the arrow D.). That is, the pillar portion 49of the packing 47 and the fold 55 press the inner peripheral face 3c ofthe main cylindrical portion 3 with a force in the direction away fromthe axis center (that is, the direction as shown by the arrow C), andthe part between the packing 47 and the main cylindrical portion 3 issealed against water (or against air). Since the pillar portion 49 ofthe packing 47 applys a force so as to reduce the diameter of the firsthole 51 and the second hole 52 to the first hole 51 side and the secondhole 52 side of the packing 47, the packing support 45, inserted intothe first hole 51 and the second hole 52, and the packing 47 arepressing each other so as to closely contact with each other. The partbetween the packing 47 and the packing support 45 is sealed againstwater (or against air).

The inner peripheral face 3c of the main cylindrical portion 3 of thesyringe body 2 is smoothly formed, and then, the piston 39, into whichthe packing 37 is inserted, is slidable in the directions as shown bythe arrows A and B in the inside space 2a of the main cylindricalportion 3.

The syringe assembly 1 is comprised as described hereinbefore. In orderto assemble the syringe assembly 1, the following steps are executed.

That is, the syringe 100, the hub 13, the needle 36, the piston 39 andthe packing 47, which are the comprising parts of the syringe assembly1, are prepared. At first, the hub 13 is inserted into the syringe 100.

That is, the hub 13 is inserted into the inside space 2a of the syringebody 2 from the opening end 3a of the syringe body 2. The insertion isexecuted so as to face the third pillar portion 20 side of the hub 13 tothe hub insertion portion 4 side of the syringe body 2 (the side of thearrow A of the figure). The hub 13 is further inserted into the hubinsertion hole 4b to the arrow A side of the figure to the positionwhere the seal taper 17 of the hub 13 abuts on the rib for holding 11 ofthe hub insertion hole 4b side. Since the outside diameter of the thirdpillar portion 20 and the second pillar portion 19 of the hub 13 issmaller than the inside diameter L1 in the portion of the rib forholding 11 in the first cylindrical portion 7, the hub 13 is smoothlyinserted to the position where the seal taper 17 abuts on the rib forholding 11 of the hub insertion hole 4b side.

A force in the direction as shown by the arrow A is further added to thehub 13 after the seal taper 17 abuts on the rib for holding 11, therebya stress in the direction perpendicular to the abutting face, and in thedirection away from the axis center P1 is added to the rib for holding11 in the point where the seal taper 17 and the rib for holding 11 ofthe hub 13 abut on each other. That is, by receiving this stress, thefirst small cylindrical portion 7 near the rib for holding 11 and thetaper 6 elastically enlarge and expand in the direction away from theaxis center P1 being perpendicular to the axis center P1, that is, inthe direction as shown by the arrow C in the figure (At the same time,the hub body 15 and the like are elastically deformed in the directionreducing the diameter of it.).

The portion near the rib for holding 11 enlarges and expands in thedirection as shown by the arrow C and the inside diameter of the firstsmall cylindrical portion 7 in the rib for holding 11 becomes to beequal to the outside diameter of the first pillar portion 16, therebythe hub 13 receiving a force pressing in the direction as shown by thearrow A advances in the direction as shown by the arrow A. The hub 13 isfurther advanced in the direction as shown by the arrow A by pressinguntil the seal taper 17 of the hub 13 abuts on the outer peripheral face9a of the insertion taper 9.

After the hub 13 advances until abutting, the hub 13 is further pressedin the direction as shown by the arrow A. By pressing, the hub 13 givesa stress in the direction perpendicular to the abutting face of theinsertion taper 9 on which the hub 13 abuts on the arrow A side, thatis, in the direction near the arrow A and in the direction near thearrow C, and the stress is transferred to the first small cylindricalportion 7 being unitedly provided with the insertion taper 9 as a stressin the direction as shown by the arrow A. Therefore, the first smallcylindrical portion 7 is lengthened in the directions as shown by thearrows A and B by elastic deformation.

As the first small cylindrical portion 7 lengthens, the rib for holding11 is moved along the outer peripheral face 16e relatively to the arrowB side against the hub 13, and the position of the rib for holding 11and the position of the chamfer portion 16b of the hub 13 are matched toeach other. Both are matched to each other, thereby the portion near therib for holding 11 of the first small cylindrical portion 7 slightlyreturns. The rib for holding 11 and the hub 13 engage with each other inthe chamfer portion 16b such that the side face 11a of the rib forholding 11 abuts on the chamfer portion 16b.

As the hub 13 advances in the direction as shown by the arrow A, thethird cylindrical portion 20 of the hub 13 reaches the hole 12a of theend wall 12 which is at the corresponding position and is inserted intothe hole 12a.

As explained heretofore, insertion of the hub 13 into the syringe 100finishes. As described before, the hub 13 is fixed by the hub insertionportion 4 balancing respective forces between the hub 13 and the hubinsertion portion 4.

The insertion operation of the hub 13 into the syringe 100 is executedby pressing the hub 13 so as to insert, and then, it is easy withoutcomplex assembling operations.

Subsequently, the packing 47 is inserted into the piston 39. In thefirst place, the first hole 51 of the packing 47 is broadened with handsor the like so as to equalize the diameter of the first hole 51 with oneof the circular plate portion 45b of the packing support 45, making useof the flexibility of the packing 47. After that, the hub engagementportion 46 side of the piston 39 is inserted in the direction as shownby the arrow A from the first hole 51 side of the packing 47. Next, thepiston 39 is further inserted until the insertion portion 46b of the hubengagement portion 46 passes and penetrates the third hole 53 of thepacking 47 in the direction as shown by the arrow A and the insertionportion 46b projects on the side of the arrow A of the taper 50 of thepacking 47, that is, the pillar portion 46a of the hub engagementportion 46 is inserted into the third hole 53 and the pillar portion 45aof the packing support 45 and the circular plate portion 45b areinserted into the first hole 51 and the second hole 52 which arerespectively broadened.

After that, the hand by which the first hole 51 is broadened is lefttherefrom so as to return the packing 47 to its natural state, therebythe insertion of the packing 47 is finished.

Subsequently, the piston 39, into which the packing 47 is inserted, isinserted into the syringe body 2.

The insertion of the piston 39 is executed in such a manner that theside where the packing 47 of the piston 39 is inserted, is inserted intothe inside space 2a of the syringe body 2 from the opening end 3a sideof the syringe body 2.

On this occasion, the outside diameter in the pillar portion 49 of thepacking 47 and the fold 55 in a natural state is bigger than the insidediameter of the main cylindrical portion 3 of the syringe body 2.However, the packing 47 can be inserted into the inside space 2a of thesyringe body 2 by reducing the outside diameter of the pillar portion 49of the packing 47 and the fold 55 making use of the flexibility of thepacking 47.

That is, the taper 50 side of the packing 47 is adjusted to the openingend 3a, and after that, the piston 39 is pressed in the direction asshown by the arrow A, thereby the packing 47 is inserted into the insidespace 2a of the syringe body 2, adjusting to the inside space 2a of thesyringe body 2, that is, reducing the outside diameter of the pillarportion 49 of the packing 47 and the fold 55.

Since the outside diameter of the inner press plate 43 and the width ofthe plate portion 40a of the piston body 40 are almost equal to theinside diameter of the main cylindrical portion 3 of the syringe body 2(or smaller), the inner press plate 43 and the piston body 40 aresmoothly inserted into the inside space 2a of the syringe body 2.

By inserting the piston 2 into the direction as shown by the arrow A,the packing 47 and the inner press plate 43 pass the position of theengagement rib 3b of the main cylindrical portion 3.

When passing the position of the engagement rib 3b, the packing 47receives the reaction against the force pressing the piston 2 in thedirection as shown by the arrow A from the engagement rib 3b, and passesreducing the outside diameter of the pillar portion 49 and the fold 55so as to equalize with the inside diameter of the engagement rib 3b ofthe main cylindrical portion 3 of the syringe body 2 by the reaction.

When the inner press plate 43 passes the position of the engagement rib3b following after the packing 47, the periphery side of the inner pressplate 43, which outside diameter is bigger than the inside diameter ofthe engagement rib 3b, abuts on the engagement rib 3b. In case ofabutting, the force pressing the piston 39 in the direction as shown bythe arrow A elastically expands the portion near the engagement rib 3bof the main cylindrical portion 3 in the direction as shown by the arrowC through the inner press plate 43, and through the engagement rib 3babutting on the inner press plate 43. Therefore, the inner press plate43 passes the position of the engagement rib 3b, broadening the insidediameter in the engagement rib 3b. After the passing, the inner pressplate 43 leaves from the engagement rib 3b, and then, no force expandingthe main cylindrical portion 3 in the direction as shown by the arrow Cacts, and the portion near engagement rib 3b of the main cylindricalportion 3 restores in the direction as shown by the arrow D.

After the packing 47 and the inner press plate 43 pass the position ofthe engagement rib 3b of the main cylindrical portion 3, the piston 39is further inserted in the direction as shown by the arrow A, and asshown in FIG. 3, the piston 39 is inserted to the position, at which thetaper 50 of the packing 47 is inserted and adjusted into the inside ofthe taper 6 of the syringe body 2, and then, the insertion of the piston39 finishes.

In such a state that the taper 50 of the packing 47 is inserted andadjusted into the inside of the taper 6 of the syringe body 2, as shownin FIG. 3, the insertion portion 46b of the hub engagement portion 46 ofthe piston 39 exists in such a manner that the spherical surface 46cside of the insertion portion 46b is in contact with the wall face 35cfacing the third taper hole 33 of the piston engagement hole 29, whichis provided with the hub 13.

Subsequently, the needle 36 is inserted into the needle insertion hole21 of the hub 13 so as to attach. That is, the needle 36 is inserted,from the rear end side of the needle 36, into the needle insertion hole21 in the direction as shown by the arrow B, as shown in FIG. 2 till therear end abuts on the wall face 16c of the hub 13 of the bottom of theneedle insertion hole 21. After the insertion, the space between the hub13 in the needle insertion hole 21 and the needle 36 is filled with theadhesive 37, and then, the adhesive 37 is hardened. Then, insertion ofthe needle 36 into the hub 13 finishes.

When the needle insertion hole 21 is filled with the adhesive 37, theadhesive 37 can flow to the bottom side of the needle insertion hole 21(that is, the arrow B side) without forming a space in the needleinsertion hole 21 to the utmost by the first taper hole 22 and thesecond taper hole 25 which are provided with the needle insertion hole21.

Assembly of the syringe assembly 1 finishes by the end of insertion ofthe needle 36.

As described hereinbefore, most operations in assembly of the syringeassembly 1 (that is, all operations excluding one for insertion of theneedle 36) are executed by pressing, and therefore, the assembly of thesyringe assembly 1 is easy without complex operations.

The syringe assembly 1 assembled as shown before, is used and, afterthat, the syringe assembly 1 is discarded as follows.

At first, the syringe assembly 1 assembled is filled with a liquidinjection medium 59. Filling it with the injection medium 59 is executedin such a manner that the main cylindrical portion 3 of the syringe body2 of the syringe assembly 1 is grasped and supported with one hand, andthe top end of the needle 36 of the syringe assembly 1 is inserted intothe injection medium 59 which is inside of a medicine bottle (notshown), and after that, the piston 39 is pulled out against the syringebody 2 in the direction as shown by the arrow B with the outer pressplate 42 of the piston 39 grasped by the other hand.

Of the inside space 2a of the syringe body 2, the space on the side ofthe arrow A rather than the packing 47 or the hub engagement portion 46,that is, a medium holding space 60 communicates with the outside of thetop end side of the needle 36, that is, inside of a medicine bottle (notshown) through the medium flow hole 36a of the needle 36, the flow hole27 and the piston engagement hole 29 of the hub 13 in the directions asshown by the arrows A and B. And, the medium holding space 60 isbroadened by pulling the piston 39 against the syringe body 2 in thedirection as shown by the arrow B, and then, the pressure of the air ofthe medium holding space 60 (or the injection medium 59) is lowered.Therefore, difference of pressure arises between the medium holdingspace 60 and the outside of the top end side of the needle 36, that is,inside of the medicine bottle (not shown), and the injection medium 59in the medicine bottle flows in the medium holding space 60 through themedium flow hole 36a of the needle 36, and the flow hole 27 and thepiston engagement hole 29 of the hub 13.

Filling with the injection medium 59 finishes in such a manner that thepiston 39 is further pulled against the syringe body 2 in the directionas shown by the arrow B so as to further broaden the medium holdingspace 60 and so as to stream a predetermined amount of the injectionmedium 59 into the medium holding space 60.

On this occasion, difference of pressure arises between the mediumholding space 60 and the outside of the medium holding space 60 at thetime of filling with the injection medium 59, and therefore, adifferential pressure force acts on the hub 13, which separates themedium holding space 60 from the outside of the medium holding space 60in the direction as shown by the arrow B.

However, a predetermined seal pressure F1 acting between the hub 13 andthe hub insertion hole 4b is set so as not to be zero or below zeroagainst the maximum differential pressure force potential in thedirection as shown by the arrow B (especially, in the seal pressure F1).Therefore, the hub 13 is supported by the rib for holding 11 in thedirection as shown by the arrow A, and the portion between the insertiontaper 9 of the hub insertion portion 4 and the seal taper 17 of the hub13 is sealed with the seal pressure F1 (which is above zero).

That is, even if the injection medium 59 in the medium holding space 60flows in the first gap space 56 between the hub 13 and the first smallcylindrical portion 7, of the hub insertion hole 4b of the hub insertionportion 4, the injection medium 59 does not pass between the insertiontaper 9 and the seal taper 17 and does not leak into the second gapspace 57 between the hub 13 and the second small cylindrical portion 10and the like since the portion between the insertion taper 9 and theseal taper 17 is sealed. In addition, outside air does not also flowfrom the second gap space 57 side to the first gap space 56 side.

On the other hand, in the packing 47, as described before, the pillarportion 49 and the fold 55 of the packing 47 are inserted into the maincylindrical portion 3 of the syringe body 2 reducing in the direction asshown by the arrow D by elastic deformation. That is, the pillar portion49 of the packing 47 and the fold 55 press the inner peripheral face 3cof the main cylindrical portion 3 with a force in the direction as shownby the arrow C, and the portion between the packing 47 and the maincylindrical portion 3 is sealed against water (against air). That is,the injection medium 59 of the medium holding space 60 does not leakinto the inside space 2a of the arrow B side of the packing 47 and thelike, passing between the packing 47 and the main cylindrical portion 3.

In addition, since the pillar portion 49 of the packing 47 and the fold55 are reduced in the direction as shown by the arrow D by elasticdeformation, the packing support 45 of the piston 39, which is insertedinto the first hole 51 and the second hole 52 of the packing 47, ispressed by the packing 47 in the direction as shown by the arrow D. Thatis, the portion between the packing 47 and the packing support 45 isclosely sealed. Therefore, the injection medium 59 of the medium holdingspace 60 can flow to the third hole 53 of the packing 47, but theinjection medium 46 does not any further pass between the packing 47 andthe packing support 45 in the second hole 52 and the first hole 51, orleaking into the inside space 2a of the arrow B side of the packing 47and the like.

After filling with the injection medium 59, the needle 36 of the syringeassembly 1 is stuck in a patient's injection portion with the maincylindrical portion 3 of the syringe assembly 1 supported with one hand.

Subsequently, the main cylindrical portion 3 of the syringe body 2 ofthe syringe assembly 1 is grasped with fingers of one hand, and thesyringe support 5 is supported and fixed in the direction as shown bythe arrow B from a plate face of the arrow A side of the syringe support5 with the fingers which grasp the main cylindrical portion 3. The outerpress plate 42 of the piston 39 is pressed in the direction as shown bythe arrow A with other fingers (the thumb) of the same hand, by whichthe main cylindrical portion 3 is grasped, so as to drive the piston 39to the syringe body 2 in the direction as shown by the arrow A. By driveof the piston 39, the capacity of the medium holding space 60 reduces,thereby the injection medium 59 in the medium holding space 60 ispressurized. By pressure, pressure difference arises between the mediumholding space 60 and the outside of the top end side of the needle 36,that is, the body of a patient. Therefore, the injection medium 59 ofthe medium holding space 60 flows into the body in the injection part ofa patient through the piston engagement hole 29 of the hub 13, the flowhole 27 and the medium flow hole 36a of the needle 36.

As described before, the injection medium 59 in the medium holding space60 is pressurized and an action force by the pressure of the injectionmedium 59 is acted on the hub 13 in the direction as shown by the arrowA from the end face 16a side of the hub 13 adjacent to the injectionmedium 59.

However, the hub 13 can sufficiently receive a reaction in the directionas shown by the arrow B, resulting from its constitution, against theaction force adding to the hub 13 in the direction as shown by the arrowA in the portion where the seal taper 17 of the hub 13 and the insertiontaper 9 of the hub insertion portion 4 are closely contacted with eachother. Therefore, the hub 13 is supported by the insertion taper 9 inthe direction as shown by the arrow B. Since the size of the sealpressure F1 between the seal taper 17 and the insertion taper 9increases by offering a reaction against the action force adding to thehub 13 in the direction as shown by the arrow A, the portion between theseal taper 17 and the insertion taper 9 is continuously sealed and watertight state (or air tight state) is maintained.

After the predetermined amount of the injection medium 59 is streamed inthe body of a patient, that is, after the taper 50 of the packing 47 isinserted and adjusted into the inside of the taper 6 of the syringe body2, and the piston 39 is driven until the insertion portion 46b of thehub engagement portion 46 of the piston 39 abuts on the third taper hole33 of the piston engagement hole 29 of the hub 13, as shown in FIG. 3,the whole syringe assembly 1 is pulled in the direction as shown by thearrow B with respect to a patient through the hand or fingers supportingthe syringe assembly 1 therewith so as to pull the needle 36 out of theinjection part of a patient.

After pulling the needle 36, the piston 39 and the hub 13 are engagedwith each other.

That is, the outer press plate 42 of the piston 39 is further pressedwith a finger in the direction as shown by the arrow A.

Just after finish of the flow operation of the injection medium 59 intoa body, the taper 50 of the packing 47 is inserted and adjusted insideof the taper 6 of the syringe body 2, the insertion portion 46b isinserted and adjusted inside of the third taper hole 33. Therefore, aforce in the direction as shown by the arrow A acts on the packing 47 asthe insertion portion 46b is advanced in the third taper hole 33 in thedirection as shown by the arrow A by driving the piston 39. Since thepacking 47 is supported by the taper 6 in the direction as shown by thearrow B, it can not move in the direction as shown by the arrow A.However, the packing 47 has flexibility, so the packing 47 remains therereducing itself in the directions as shown by the arrows A and B byelastic deformation so that the only insertion portion 46b moves in thedirection as shown by the arrow A.

Since a force in the direction as shown by the arrow A is added to thepiston 39 by pressing pressure, a pressing force in the direction asshown by the arrow A is added to the insertion portion 46b of the hubengagement portion 46. In addition, by this pressing pressure force, theforces in the direction in which the insertion portion 46b and the wallface 35c of the hub 13 facing the third taper hole 33 abut on eachother, that is, in the direction perpendicular to the wall face 35c, acton each other between the insertion portion 46b and the hub 13 which areabutted on each other. Resulting from its constitution, the projection35a of the hub 13 on which the insertion portion 46b abuts in the wallface 35c elastically deforms enlarging the diameter in an apex of theprojection 35a, that is, the diameter in the boundary portion 35. At thesame time, the insertion portion 46b elastically deforms reducing thediameter of the section perpendicular to the axis center P1.

The piston 39 is further pressed in the direction as shown by the arrowA so as to further advance the insertion portion 46b into the thirdtaper hole 33 in the direction as shown by the arrow A. That is, theinsertion portion 46b passes the boundary portion 35 in the direction asshown by the arrow A, reducing the diameter of the insertion portion 46band enlarging the diameter of the boundary portion 35 so as tocorrespond the diameter of the insertion portion 46b with one of theboundary portion 35. After the whole insertion portion 46b completelypasses the boundary portion 35, the press of the piston 39 finishes.

The whole insertion portion 46b completely passes the boundary portion35, thereby the insertion portion 46b is inserted in the space formed bythe first taper hole 30, the pillar hole 31 and the second taper hole 32as shown by the two-dot chain line of FIG. 3 so as to adjust. The pillarportion 46a extending on the arrow B side of the insertion portion 46bexists penetrating the boundary portion 35 in the directions as shown bythe arrows A and B. Then, the piston 39 and the hub 13 engage with eachother.

The pressing force in the direction as shown by the arrow A acts on theinsertion portion 46b, thereby the pressing force in the direction asshown by the arrow A acts on the hub 13 also. However, the hub 13 issupported in the direction as shown by the arrow B in the seal taper 17by the insertion taper 9 of the hub insertion portion 4 with the hand bywhich the syringe body 2 is supported (or is supported by the wall face12b of the end wall 12 in the end face 19a of the second pillar portion19), and then receives a reaction in the direction as shown by the arrowB against the pressing force from the seal taper 17 (or the end wall12). That is, the hub 13 does not almost move in the direction as shownby the arrow A or the like if receiving the pressing force. Therefore,the hub 13 is not pulled out of the hole 12a of the end wall 12 in thedirection as shown by the arrow A.

After the piston 39 and the hub 13 are engaged with each other, the maincylindrical portion 3 of the syringe body 2 is supported with one hand,the outer press plate 42 is pulled against the syringe body 2 in thedirection as shown by the arrow B with the other hand. By pulling theouter press plate 42, the action force in the direction as shown by thearrow B acts on the piston 39 and the insertion portion 46b of the hubengagement portion 46.

On this occasion, as shown in FIG. 3, this action force acts such thatthe forces are pressed to each other between the end portion of thearrow B side of the insertion portion 46b and the portion of the rootside of the projection 35a. However, the end portion of the arrow B sideof the insertion portion 46b and the portion of the root side of theprojection 35a are hard to elastically deform for their constitution.Therefore, the insertion portion 46b is not pulled out of the pistonengagement hole 29 passing through the boundary portion 35.

In this way, the action force in the direction as shown by the arrow Bacts on the insertion portion 46b, thereby the action force in thedirection as shown by the arrow B acts on the hub 13 by the insertionportion 46b engaged in the piston engagement hole 29. However, the hub13 is not supported by the rib for holding 11 in the direction as shownby the arrow A against the action force in the direction as shown by thearrow B acting on the hub 13. Then, the portion near the rib for holding11 of the first small cylindrical portion 7 (or the taper 6) receivesthe action force in the rib for holding 11 through the chamfer portion16b of the hub 13, thereby it enlarges and expands in the direction asshown by the arrow C in the figure.

The action force in the direction as shown by the arrow B is furtheradded to the piston 39 and the portion near the rib for holding 11 ofthe first small cylindrical portion 7 (or the taper 6) further enlargesand expands in the direction as shown by the arrow C in the figure,thereby the hub 13 is pulled out to the direction as shown by the arrowB passing through the portion of the rib for holding 11 of the firstsmall cylindrical portion 7 which inside diameter enlarges rather thanoutside diameter L1' of the first pillar portion 16 of the hub 13. Thepiston 39 is continuously pulled in the direction as shown by the arrowB, thereby the hub 13 is further advanced in the direction as shown bythe arrow B, and the hub 13 is pulled until it is completely pulled outof the first small cylindrical portion 7 in the direction as shown bythe arrow B.

On this occasion, the outside diameter L1' of the first pillar portion16 of the hub 13 is smaller than the inside diameter L1 of the firstsmall cylindrical portion 7, and the outside diameter L2' of the secondpillar portion 19 is smaller than the inside diameter L2 of the secondsmall cylindrical portion 10. In addition, since the seal taper 17 andthe insertion taper 9 are disposed so as not to interfere with thedirection in which the hub 13 is pulled out, when the hub 13 is pulledout, the hub 13 and the hub insertion portion 4 are contacted with eachother only between the chamfer portion 16b (or the outer peripheral face16e of the first pillar portion 16) and the rib for holding 11.Therefore, the pulling operation can be easily executed with a smallforce after the chamfer portion 16b and the rib for holding 11 aredisengaged from each other.

The piston 39 is further pulled and the needle 36, which is inserted andfixed on the arrow A side of the hub 13, inserts into the hub insertionhole 4b from the hole 12a of the end wall 12 in the direction as shownby the arrow B, and further inserts in the inside space 2a of the maincylindrical portion 3 in the direction as shown by the arrow B, and thepiston 39 is pulled in the direction as shown by the arrow B such thatthe top end of the needle 36 is completely inserted into the insidespace 2a.

The piston 39 is further pulled till the inner press plate 43 abuts onthe engagement rib 3b of the main cylindrical portion 3 of the syringebody 2, as shown in FIG. 4, and the piston 39 is stopped.

On this occasion, the inner press plate 43 of the piston 39 is engagedwith and stopped by the engagement rib 3b so as to prevent the needle 36inserted into the hub 13 engaged with the piston 39 from springing tothe outside the syringe body 2, by excessively pulling the piston 39 bymistake. In addition, the accident of secondary infection or the likegenerating from the hurt of hands and the like by the needle 36 can beprevented.

And, in such a state that the inner press plate 43 of the piston 39 isengaged with and stopped by the engagement rib 3b, the position of thenotch 41 formed on the piston body 40 of the piston 39 is adjusted tothe position of the opening end 3a of the syringe body 2 in thedirection as shown by the arrows A and B, as shown in FIG. 4.

Subsequently, while the syringe body 2 is fixed with one hand, thepiston 39 is grasped with the other hand, and as shown in FIG. 4, aforce in the direction as shown by the arrow C is added to the piston39. By adding a force in the direction as shown by the arrow C to thepiston 39 with respect to the syringe body 2, bending stress is added tothe piston body 40 with the engagement rib 3b and the opening end 3a ofthe syringe body 2 as a supporting point, and then the piston body 40 isbroken in the notch 41, in which the structure of the piston body 40 isrelatively weak with respect to bending stress, and the piston body 40is separated into the arrow A side portion and the arrow B side portionforming a boundary with the notch 41.

By making the engagement rib 3b and the opening end 3a of the syringebody 2 a supporting point, bending stress can be effectively added tothe piston body 40 using a principle of a lever. In addition, since theposition of the notch 41 is at the position of the opening end 3a, thatis, the position of the supporting point, the bending stress adding tothe piston body 40 is effectively added to the portion of the notch 41.Therefore, the piston body 40 can be easily bent so as to be separated,that is, easily folded and taken.

Subsequently, the portion of the syringe body 2 side folded and takenand the portion of the outer press plate 42 of the piston 39 aredisposed of so as to be discarded.

Since the needle 36 is completely inserted and stored in the insidespace 2a of the syringe body 2 being held with the top end portion ofthe piston 39 remaining in the inside space 2a, there is no fear ofhurting hands or the like and being secondarily infected from a wound bythe needle 36. Therefore, waste disposal can be safety executed. And,the piston 39 is folded and taken, thereby the syringe assembly 1 foldedand taken is not bulky, and then waste disposal can be smoothlyexecuted. As described before, the use of the syringe assembly 1 andwaste disposal after use all finish.

As described heretofore, the hub 13 of the syringe assembly 1 has thehub body 15 in the shape of a cylinder, through which the hub 13 isinserted into the hub insertion hole 4b and is pulled out of the hubinsertion hole 4b to the syringe body 2. The chamfer portion 16b isprovided with the hub body 15 so as to engage with the inner face of thehub insertion hole 4b. The piston engagement hole 29 is provided withthe end face 16a of the hub body 15 so as to engage with the piston 39.The seal taper 17, which outside diameter is made narrower for the endface 20a side of the hub body 15, is annularly provided with the hubbody 15 so as to abut on and contact with the inner face of the hubinsertion hole 4b.

Then, the hub 13 and the hub insertion hole 4b can be contacted witheach other through the seal taper 17 and the chamfer portion 16b. It iseasy to attach and detach the hub 13 to and from the hub insertion hole4b. In addition, a predetermined seal efficiency and a predeterminedholding efficiency can be exercised between the hub 13 and the hubinsertion hole 4b, and the disposing operation of the hub 13 in case ofassembly and the pulling operation of the needle 36 used into thesyringe assembly 1 can be smoothly and easily executed.

The connecting structure of the hub 13 is as follows. The hub body 15 isattachably and detachably inserted into the hub insertion hole 4b so asto insert into the hub insertion hole 4b and to pull out the hubinsertion hole 4b to the syringe body 2. The insertion taper 9, whichinside diameter is made narrower for the top end side of the syringebody 2, is annularly provided with the hub insertion hole 4b. And, theseal taper 17 of the hub body 15 is provided with the hub insertion hole4b so as to be contacted with the insertion taper 9 with the sealpressure F1. The rib for holding is provided with the inner peripheralface of the hub insertion hole 4b so as to engage with the chamferportion 16b of the hub body 15 such that the hub body 15 is free to beheld and released with the holding force F2.

Then, the hub 13 and the inner peripheral face of the hub insertion hole4b are contacted with each other through the seal taper 17 and theinsertion taper 9, and the chamfer portion 16b and the rib for holding11. It is easily executed to attach and detach the hub 13 to and fromthe hub insertion hole 4b, and the assembly operation of the syringeassembly 1 can be effectively executed. In addition, the direction inwhich the hub 13 is pulled is one in which the seal taper 17 isseparated from the insertion taper 9 when the needle 36 used iswithdrawn to the syringe assembly 1. Therefore, the hub 13 can bewithdrawn inside of the syringe assembly 1 with a small pulling forcemaking use of the seal pressure F1. The discarding operation of the usedsyringe assembly 1 can be smoothly and easily executed.

Besides, the syringe assembly 1 having the connecting structure of thehub 13, above described, can be withdrawn to the inside space 2a of thesyringe 100 together with the needle 36 by engaging the hub 13 with thehub engagement portion 46 of the piston 39 after injection. The usedneedle 36 can be easily withdrawn to the inside space 2a of the syringe100 by only pushing and pulling the piston 39, in a similar way to theoperation of an usual syringe assembly, and then its operation is easyfor every one. Besides, there is no danger of error operation and safetyis secured.

The piston 39 is comprised such that the piston body 40 is free to bebent and taken between the outer press plate 42 and the inner pressplate 43. Therefore, the needle 36 can remain such that the top endportion of the piston 39 holding the needle 36 is held in the insidespace 2a of the syringe 100 by bending and taking the piston 39, therebyit is not operable from the outside. High safety is secured in case ofdisposal operation after that.

In addition, the engagement rib 3b is provided with the syringe body 2so that the inner press plate 43 of the piston 39 is not pulled out ofthe syringe body 2. Therefore, it is possible to prevent an operatorfrom hurting with the needle 36 used by inadvertently pulling the piston39 out of the syringe body 2 when the piston 39 is moved together withthe needle 36. Therefore, high safety is secured.

The notches 41 are provided with the piston body 40 of the piston 39.Then, the operation of bending and taking of the piston 39 can be easilyexecuted by making use of the notches 41.

In addition, the notch 41 is formed so as to be positioned at theopening end 3a of the syringe body 2 when the piston 39 abutting on theengagement rib 3b. Therefore, the piston 39 is pulled till it abuts onthe engagement rib 3b, and after that, the piston 39 can be immediatelybend and taken by making use of the opening end 3a, and the operation ofstoring and remaining the needle 36 in the inside space 2a of thesyringe 100 can be successively executed. Therefore, the operations ofinjection and disposal can be effectively executed.

The hub 13 explained in the above-mentioned embodiment, is comprisedsuch that the held portion of the hub is the chamfer portion 16b of theperiphery of the end face 16a. However, the hub of the present inventionmay be comprised such that the held portion of the hub is formed at aposition different from one of the end face 16a.

That is, as shown in FIG. 5, the hub 13 may be comprised such that aheld groove 61 in the shape of a groove is annularly formed on the outerperiphery face 16e side of the first pillar portion 16 of the hub 13. Incase where the held groove 61 is annularly formed, the rib for holding11 of the hub insertion hole 4b side is formed at the positioncorresponding to the held groove 61 (On this occasion, the sectionalform of the groove 61 can be adequately decided. Besides, it is ofcourse possible that the sectional form is comprised so as to exerciseseal action between the groove 61 and the rib 11. This point is similarto the case of FIG. 6 described hereinafter).

In case where a held portion is the held groove 61 also, a predeterminedholding efficiency can be exercised between the hub 13 and the hubinsertion hole 4b by engaging the held groove 61 and the rib for holding11 with each other.

The hub 13 explained in the two embodiments above-mentioned is comprisedsuch that the holding portion of the hub insertion hole is in the shapeof a projection. However, it is possible that the holding portion of thehub insertion hole is formed in the shape of a groove. In case where theholding portion of the hub insertion hole is formed in the shape of agroove, the held portion of the hub corresponded to and engaged with theholding portion of the hub insertion hole is formed in the shape of aprojection.

That is, as shown in FIG. 6, a holding groove 62 may be annularly formedin the shape of a groove on the inner peripheral face 7a side of thefirst small cylindrical portion 7 of the hub insertion hole 4b, and aheld rib 63 may be annularly formed in the shape of a projection so asto correspond to the holding groove 62 on the outer periphery face 16eside of the first pillar portion 16 of the hub 13.

In case where the holding portion is the holding groove 62 and the heldportion is the held rib 63, a predetermined holding efficiency can beexercised between the hub 13 and the hub insertion hole 4b by engagingthe holding groove 62 and the held rib 63 with each other.

Any of the holding portion of the hub insertion hole and the heldportion of the hub, explained in the respective embodimentsabove-mentioned, is annularly formed along the hub insertion hole or thehub. However, the holding portion and the held portion may be formed inany shape, such as point shape or broken line shape, as well as annularshape, as long as a predetermined holding efficiency can be exercisedbetween the hub insertion hole and the hub by engaging both with eachother.

Another embodiment of the present invention will now be explainedhereinafter.

A syringe assembly 101 according to the present invention has a syringeX100 made of resin, as shown in FIG. 8. A syringe body 102 is providedwith the syringe X100 (FIG. 8 is a typical cross section of the syringeassembly 101, but a side is shown in a part of a piston 123, describedhereinafter, not the section, for convenience.). A main cylindricalportion 103, cylindrically formed, is provided with the syringe body102. A direction of an axis center of the main cylindrical portion 103,that is, the reciprocating directions parallel to an axis center XP1 arean arrow XA direction in the figure (or the left direction of the paperof FIG. 8) and an arrow XB direction (or the right direction of thepaper of FIG. 8).

On the outer periphery side of the main cylindrical portion 103, asyringe support 105 is provided near an opening end 103a of the arrow XBside of the main cylindrical portion 103 (the right side of the paper ofFIG. 8), in such a manner as forming a flange of the main cylindricalportion 103. On an inner peripheral face 103c side of the maincylindrical portion 103, an engagement rib 103b, projecting in thedirection for the axis center XP1 of the main cylindrical portion 103,that is, the direction as shown by the arrow XD of the figure, isannularly formed near the opening end 103a along the inner peripheralface 103c.

On the arrow XA side of the main cylindrical portion 103 (the left sideof the paper of FIG. 8) a taper 106 in the shape of a funnel, whichinside is made narrower for the direction as shown by the arrow XA, isformed unitedly connecting with the main cylindrical portion 103.

The inside of the main cylindrical portion 103 and the inside of thetaper 106 communicate with each other in the directions as shown by thearrows XA and XB, and the space into which both insides are combined isan inside space 102a of the syringe body 102.

On the side of the arrow XA of the taper 106, that is, on the side ofthe top of the syringe body 102, as shown in FIGS. 7 and 8, a hubinsertion portion 104 is formed unitedly connecting with the taper 106,and the hub insertion portion 104 has a small cylindrical portion 107.The small cylindrical portion 107 is formed unitedly connecting with thetaper 106 and coaxial with the main cylindrical portion 103. The insidediameter of the small cylindrical portion 107 is smaller than one of themain cylindrical portion 103.

The inside of the small cylindrical portion 107 is a hub insertion hole104b. At the hub insertion hole 104b, a hub stop rib 107d is formedprojecting for the axis center XP1. The hub stop rib 107d is annularlyformed along a smooth inner peripheral face 107a of the smallcylindrical portion 107. A section of a plane including the axis centerXP1 of the hub stop rib 107d (that is, a section as shown in FIG. 7)forms an arc.

On the other hand, a stiffening rib 107c is annularly formed at theposition corresponding to the hub stop rib 107d putting the smallcylindrical portion 107 therebetween on an outer peripheral face 107fside of the small cylindrical portion 107.

As shown in FIG. 7 or FIG. 10, an end wall 108, which outside diameteris equal to one of the small cylindrical portion 107 is provided in theshape of a disc with the small cylindrical portion 107. The end wall 108is provided united with the small cylindrical portion 107 such that thewall face 108b of the arrow XB side of the end wall 108 and an endportion 107b of the arrow XA side of the small cylindrical portion 107are contacted with each other. A hole 108a having a circular section,which center is the axis center XP1, is provided with the end wall 108penetrating both front and back wall faces of the end wall 108 in thedirections as shown by the arrows XA and XB. The arrow XA side of thehole 108a is taperingly formed such that a sectional inside diameter ismade big for the arrow XA direction.

As shown in FIG. 7 or FIG. 10, three slits 150 are formed extending tothe end wall 108 and the small cylindrical portion 107. The slits 150are formed extending in a radial direction with respect to the axiscenter XP1 in the end wall 108, that is, in the directions as shown bythe arrows XC and XD in FIG. 10 (The arrow XC direction is opposite tothe arrow XD direction.) and communicating with the hole 108a providedwith the end wall 108, and are formed parallel to the directions asshown by the arrows XA and XB in the small cylindrical portion 107. Theslits 150 are formed at the positions on the arrow XA side rather thanthe hub stop rib 107d and the stiffening rib 107c so as not to reach thehub stop rib 107d and the stiffening rib 107c.

The hub insertion portion 104 is comprised as explained before. Thesyringe X100 is comprised such that the syringe support 105, the maincylindrical portion 103 comprising the syringe body 102, the taper 106and the hub insertion portion 104 are unitedly provided.

A hub 109 made of resin, which is harder than the syringe X100, isprovided with the hub insertion hole 104b of the hub insertion portion104. As shown in FIG. 7, the hub 109 has a hub body 190. A main pillarportion 110 in the shape of a cylinder, which longitudinal direction isparallel to the directions as shown by the arrows XA and XB, which axiscenter is the axis center XP1, is provided with the hub body 190.

On a smooth outer peripheral face 110f side of the main pillar portion110, the hub stop groove 110c is formed. The hub stop groove 110c isannularly formed along the outer periphery side of the main pillarportion 110.

On an end face 110a of the arrow XA side of the main pillar portion 110,a small pillar portion 111 is provided extending in the directions asshown by the arrows XA and XB, coaxial and united with the main pillarportion 110.

As shown in FIG. 7, the hub 109 is provided such that the main pillarportion 110 of the hub 109 is inserted into the hub insertion hole 104bof the hub insertion portion 104, and the small pillar portion 111 ofthe hub 109 is inserted into the hole 108a of the end wall 108 so as topenetrate it. The hub stop rib 107d of the hub insertion portion 104 andthe hub stop groove 110c of the hub 109 are at the positionscorresponding to each other so as to adjust. Therefore, the hub stop rib107d engages with the hub stop groove 110c such that the top end side inthe shape of an arc of the arrow XD side is inserted into the hub stopgroove 110c which is at the position corresponding to and matching withthe hub stop rib 107d.

Since the width of the hub stop rib 107d in the directions as shown bythe arrows XA and XB is broader than one of the hub stop groove 110c inthe directions as shown by the arrows XA and XB, the hub stop rib 107dengages with the hub stop groove 110c abutting on opening ends 110e,110e of both sides of the hub stop groove 110c in the directions asshown by the arrows XA and XB directions in seal portions 107e, 107e ofthe top being in the shape of a circular arc in the directions as shownby the arrows XA and XB.

On this occasion, the inner peripheral face 107a of the smallcylindrical portion 107 does not contact with the outer peripheral face110f of the hub 109 in the portions excluding the hub stop rib 107d, anda gap space 149 is formed between the inner peripheral face 107a and theouter peripheral face 110f (However, the portions excluding the hub stoprib 107d of the inner peripheral face 107a of the small cylindricalportion 107 and the outer peripheral face 110f of the hub 109 maycontact with each other as long as the hub 109 can be easily insertedinto the hub insertion portion 104 and the hub 109 can be easily pulledout of the hub insertion portion 104, both explained hereinafter.).

An end face 110b of the arrow XB side of the main pillar portion 110 ofthe hub 109 is positioned on the arrow XA side rather than the boundarybetween the hub insertion hole 104b and the inside space 102a (that is,the boundary between the inside of the small cylindrical portion 107 andthe inside of the taper 106). A space on the arrow XB side rather thanthe end face 110b of the inside of the hub insertion hole 104b is a holespace 104a.

On the other hand, the hub insertion portion 104 is elastically deformedexpanding the small cylindrical portion 107 in the direction as shown bythe arrow XC in such a state that the hub 109 is provided with the hubinsertion hole 104b. That is, a restoring force by elastic deformationof the small cylindrical portion 107 is transferred to the hub 109through the hub stop rib 107d of the small cylindrical portion 107. Thatis, between the hub stop rib 107d and the hub 109, predetermined sealpressures XF1 by the restoring force act in the portion between the sealportion 107e and the opening end 110e of the hub stop groove 110c, whichare contacted with each other, and then the portion between the sealportion 107e and the opening end 110e is in a water tight state or anair tight state.

Rigidity of the hub stop rib 107d and the portion near thereof isincreased in the small cylindrical portion 107 by the stiffening rib107c which is provided the position corresponding to the hub stop rib107d putting the small cylindrical portion 107 therebetween, and then apredetermined restoring force by elastic deformation of the smallcylindrical portion 107 can be effectively obtained (No stiffening rib107c may be useful.).

As shown in FIG. 7, a needle insertion hole 112 is provided with the hub9. By provision of the needle insertion hole 112, a circular opening112a, which center is the axis center XP1 is formed at an end face 111aof the arrow XA side of the small pillar portion 111 of the hub 109, andthe opening 112a extends from the end face 111a in the direction asshown by the arrow XB. An end portion 112b of the arrow XB side of theneedle insertion hole 112 reaches the inside of the main pillar portion110. The end portion 112b contacts with a wall face 110d of the mainpillar portion 110. A taper is adequately formed such that the diameterof the needle insertion hole 112 is made narrower for the direction asshown by the arrow XB in the needle insertion hole 112.

On the other hand, a flow hole 113 is provided with the main pillarportion 110 of the hub 109 adjacent to the arrow XB side of the needleinsertion hole 112. The flow hole 113, which center is the axis centerXP1 and which diameter is smaller than one of the needle insertion hole112 in the end portion 112b, is formed in the shape of a cylinder. Theflow hole 113 communicates with the needle insertion hole 112 forming acircular opening at the wall face 110d of the main pillar portion 110.

A piston engagement hole 115, which section perpendicular to the axiscenter XP1 is a circle, is provided with the main pillar portion 110 ofthe hub 109 communicating with and adjacent to the arrow XB side of theflow hole 113, coaxial with the axis center XP1. An opening 117b, whichis open outside in the end face 110b of the main pillar portion 110, isformed on the arrow XB side of the piston engagement hole 115.

The piston engagement hole 115 is comprised of two parts, that is, anengagement holding portion 116 of the arrow XA side and an introducingportion 117 of the arrow XB side. The engagement holding portion 116having almost cylindrical shape, coaxial with the axis center XP1, hastapers which respective diameters are made narrower for the directionsas shown by the arrows XA or XB in both end portions of the arrows XAand XB sides. The end portion side of the arrow XA of the engagementholding portion 116 connects with and is adjacent to the flow hole X113.

The end portion of the arrow XB side of the engagement holding portion116 connects with and is adjacent to the introducing portion 117. Thediameter of the introducing portion 117 is made bigger for the directionas shown by the arrow XB. Therefore, the portion between a wall face116a facing the engagement holding portion 116 and a wall face 117afacing the introducing portion 117 of the main pillar portion 110 formsa projection 120 projecting for the axis center XP1 with a boundaryportion 119 between the engagement holding portion 116 and theintroducing portion 117 as an apex.

On the other hand, a needle 121 is inserted into the needle insertionhole 112 of the hub 109, as shown in FIG. 7 or FIG. 8. A top side of theneedle 121 is positioned outside of the syringe body 102 and the needle121 is inserted into the needle insertion hole 112 from a rear end sideof it. The rear end of the needle 121 abuts on the wall face 110d formedon the arrow XB side of the needle 112. A medium flow hole 121a providedpenetrating from the top end of the needle 121 to the rear end side andthe flow hole 113 connect with and are adjacent to each other in thedirections as shown by the arrows XA and XB.

An adhesive 122 is injected into the needle insertion hole 112 fillingthe portion between the needle 121 and the hub 109 therewith, and ishardened.

The piston 123 is provided with the syringe assembly 101, as shown inFIG. 7 or FIG. 8 (FIG. 8 is a typical sectional view of the syringeassembly 101, but with respect to a piston body 125, an outer pressplate 127, an inner press plate 129, a packing support 130, a hubengagement portion 131 of the piston 123, described hereinafter, eachsection is not shown, but each side is shown, for convenience.).

The piston 123 has the bar-shaped piston body 125 extending in thedirections as shown by the arrows XA and XB. The piston body 125 iscomprised such that two congruent plate portions 125a, each which is aplate shaped rectangle especially long in the directions as shown by thearrows XA and XB, are unitedly cross provided with each other such thatthe sections thereof form the shape of a cross. The width perpendicularto the directions as shown by the arrows XA and XB of the plate face ofthe plate portion 125a is almost equal to the inside diameter in theengagement rib 103b of the main cylindrical portion 103, and the pistonbody 125 is inserted into the main cylindrical portion 103 through theopening end 103a from the arrow XA side of the piston body 125.

On each plate portion 125a of the piston body 125, notches 126 areformed from both side portions of the respective plate portions 125a,125a in the direction of the axis center (that is, the axis center XP1)of the piston body 125 in the shape of a wedge near the direction asshown by the arrow XA. Four notches 126 are provided at the positionsadjusted one another in the directions as shown by the arrows XA and XB.

The outer press plate 127, which plate face is a circular plateperpendicular to the directions as shown by the arrows XA and XB, isprovided on the end portion side of the arrow XB side of the piston body125, being united with the piston body 125.

The inner press plate 129, which plate face is a circular plateperpendicular to the directions as shown by the arrows XA and XB, isprovided on the end portion side of the arrow XA side of the piston body125 being united with the piston body 125 and coaxial with the pistonbody 125 (Therefore, the inner press plate 129 is positioned inside themain cylindrical portion 103.). The diameter of the inner press plate129 is almost equal to the inside diameter of the main cylindricalportion 103 (Therefore, the diameter of the inner press plate 129 isbigger than the inside diameter in the engagement rib 103b of the maincylindrical portion 103.).

As shown in FIG. 8, the packing support 130 is provided with the innerpress plate 129 on the arrow XA side. A pillar portion 130a in the shapeof a circular cylinder, which extends in the directions as shown by thearrows XA and XB, is provided with the packing support 130, coaxial withthe inner press plate 129. The diameter of the pillar portion 130a issmaller than one of the inner press plate 129, and the pillar portion130a is provided on the arrow XA side of the inner press plate 129,being united with the inner press plate 129. On the arrow XA side of thepillar portion 130a, as shown in FIG. 7 or FIG. 8, an insertion pillarportion 130b in the shape of a circular cylinder, extending in thedirections as shown by the arrows XA and XB, coaxial with the pillarportion 130a, having an outside diameter almost equal to an insidediameter of the small cylindrical portion 107, is provided united withthe pillar portion 130a.

The hub engagement portion 131 is provided on the arrow XA side of theinsertion pillar portion 130b. As shown in FIG. 7 or FIG. 9, a pillarportion 131a being in the shape of a cylinder is provided with the hubengagement portion 131, extending in the directions as shown by thearrows XA and XB, coaxial with the insertion pillar portion 130b. Thediameter of the pillar portion 131a is smaller than one of the insertionpillar portion 130b. The pillar portion 131a is provided on the arrow XAside of the insertion pillar portion 130b, united with the insertionpillar portion 130b. A semi-spherical insertion portion 131b, whichdiameter is bigger than one of the pillar portion 131a is provided onthe arrow XA side of the pillar portion 131a, united with the pillarportion 131a, directing a spherical surface 131c side to the arrow XAside. A plurality of grooves 132 are provided in the shape of a stripewith the insertion portion 131b along the spherical face 131c extendingfrom the top end portion of the arrow XA side to the arrow XB side.

The diameter of the pillar portion 131a is almost equal to the insidediameter of the boundary portion 119 of the piston engagement hole 115provided with the hub 109. Therefore, the diameter of the insertionportion 131b is bigger than one of the boundary portion 119. The side ofthe insertion portion 131b is set so as to fully be inserted into andheld by the engagement holding portion 116 of the piston engagement hole115.

On the other hand, a packing 133 made of flexible resin is supportinglyprovided with the packing support 130, as shown in FIG. 8. The packing133 has a packing body 135 inserted inside of the main cylindricalportion 103 of the syringe X100 so as to adjust. An engagement hole 135ais provided with the packing body 135 penetrating the packing body 135in the directions as shown by the arrows XA and XB. The pillar portion130a of the packing support 130 and a part of the insertion pillarportion 130 penetrate the engagement hole 135a. That is, the packing 133engages with the packing support 130 such that the packing support 130penetrates the engagement hole 135a, and is provided being supported bythe packing support 130 by the engagement. The packing 133 in theengagement hole 135a and the packing support 130 are closely contactedwith each other, that is, the portion therebetween is sealed againstwater or against air. The end portion of the arrow XB side of thepacking body 135 abuts on the inner press plate 129 so as to easilyreceive a force in the direction as shown by the arrow XA by the innerpress plate 129.

The arrow XA side of the packing body 135 has such a shape that it canbe inserted and adjusted into the inside of the taper 106 of the syringebody 102 in a natural state, that is, the arrow XA side of it is a taper135b taperingly formed, reducing its outside diameter for the directionas shown by the arrow XA. A portion of the arrow XA side of theinsertion pillar portion 130b of the packing support 130 which is in astate of penetrating the engagement hole 135a projects on the arrow XAside rather than the taper 135b.

In such a state that the taper 135b of the packing 133 is inserted andadjusted into the inside of the taper 106 of the syringe body 102 in anatural state, as shown in FIG. 7, the form of the packing support 130and the packing 133 is set in such a manner that the insertion pillarportion 130b of the packing support 130 engaging with the packing 133 isinserted into the hub insertion hole 104b of the syringe body 102 andthe spherical face 131c of the insertion portion 131b of the hubengagement portion 131 contacts with the wall face 117a facing theintroducing portion 117 of the piston engagement hole 115.

The outside diameter of the packing body 135 of the packing 133 isalmost equal to one of the inner press plate 129. However, on the outerperiphery side of the packing body 135, annular folds 135c are doubleformed, being arranged in the directions as shown by the arrows XA andXB along the outer periphery of the packing body 135. Therefore, thepacking 133 is inserted into the main cylindrical portion 103 of thesyringe body 102 reducing the portion near the fold 135c of the packingbody 135 in the direction for the axis center XP1, that is, in thedirection as shown by the arrow XD by elastic deformation. That is, thepacking 133 and the main cylindrical portion 103 are closely contactedwith each other in the fold 135c and the inner peripheral face 103c. Theportion between the packing 133 and the main cylindrical portion 103 issealed against water or against air.

The inner peripheral face 103c of the main cylindrical portion 103 ofthe syringe body 102 is smoothly formed, and then the piston 123 intowhich the packing 133 is inserted, is free to slide in the directions asshown by the arrows XA and XB directions in the inside space 102a of themain cylindrical portion 103.

The syringe assembly 101 is comprised as explained hereinbefore. Inorder to assemble the syringe assembly 101, the following steps areexecuted.

That is, the syringe X100, the hub 109, the needle 121, the piston 123and the packing 133, which are the comprising parts of the syringeassembly 101, are prepared. At first, the packing 133 is inserted intothe piston 123.

That is, the packing support 130 of the piston 123 is inserted into theengagement hole 135a by pressurizing it from the engagement portion 131making use of flexibility of the packing 133 in such a manner that theinsertion portion 131b of the hub engagement portion 131 of the piston123 is adjusted to the opening end of the arrow XB side in the figure ofthe engagement hole 135a of the packing 133, and in the afore-mentionedstate, the piston 123 is pressed to the packing 133 in the direction asshown by the arrow XA. The packing support 130 is engaged with theengagement hole 135a in a predetermined state in such a manner that thepacking support 130 is inserted into the engagement hole 135a bypressurizing it, thereby insertion of the packing 133 to the piston 123finishes.

Subsequently, the piston 123 into which the packing 133 is inserted, isinserted into the syringe body 102.

That is, after the taper 135b side of the packing 133 inserted thepiston 123 therein is adjusted to the opening end 103a, the piston 123is pressed to the syringe body 102 in the direction as shown by thearrow XA, thereby the packing 133 is inserted into the inside space 102aof the syringe body 102 while sliding, and the piston 123 inserted thepacking 133 therein is inserted into the syringe body 102.

The piston 123 is inserted in the direction as shown by the arrow XA,thereby the packing 133 and the inner press plate 129 pass the positionof the engagement rib 103b, of the main cylindrical portion 103, whichinside diameter is reduced. When the packing 133 and the inner pressplate 129 pass the position of the engagement rib 103b having the insidediameter smaller than the outside diameter of the packing 133 and theinner press plate 129, the piston 123 is pressed with a further bigforce in the direction as shown by the arrow XA, thereby the stress bythis press is given to the engagement rib 103b from the inner pressplate 129 so as to enlarge the inside diameter of the portion near theengagement rib 103b of the main cylindrical portion 103, or reactionforce against this press is given to the packing 133 from the engagementrib 103b so as to make it pass there adequately reducing the outsidediameter of the packing 133 by the reaction force.

The piston 123 is further inserted slidingly in the direction as shownby the arrow XA, and the piston 123 is inserted into the position wherethe taper 135b of the packing 133 is adjusted to the inside of the taper106 of the syringe body 102, and then insertion of the piston 123finishes.

Subsequently, the hub 109 is inserted into the hub insertion hole 104bfrom the hole 108a side of the end wall 108 of the hub insertion portion104.

That is, the end face 110b of the arrow XB side of the hub 109 isadjusted to the hole 108a of the end wall 108, and in theafore-mentioned state, the hub 109 is pressed in the direction as shownby the arrow XB. As described before, three slits 150 are provided onthe end wall 108 side of the hub insertion portion 104, and the end wall108 side of the hub insertion portion 104 is divided into three parts.By pressing, the periphery near the end face 110b side of the hub 109and a taper face 108c in the shape of a taper, facing the hole 108a ofthe end wall 108 are abutted on and pressed to each other, and an actionforce to elastically bend and deform the divided portions in thedirection as shown by the arrow XC acts on the divided portions of thehub insertion portion 104. Since the divided portion of the hubinsertion portion 104 is easy to elastically bend and deform in thedirection as shown by the arrow XC for its structure in comparison withthe other parts of the hub insertion portion 104 which are not divided,the divided portion of the hub insertion portion 104 elastically bendsand deforms in the direction as shown by the arrow XC as the hub 109 ispressed so as to enlarge the diameter of the hole 108a.

The hub 109 is further pressed so as to enlarge the diameter of the hole108a to make it equal to the outside diameter of the main pillar portion110 of the hub 109. Then the hub 109 is inserted into the hub insertionhole 104b, and the main pillar portion 110 of the hub 109 is completelyinserted into the hub insertion hole 104b, and then the pressing andinsertion of the hub 109 are stopped.

Since the gap space 149 is formed between the outer peripheral face 110fof the main pillar portion 110 of the hub 109 and the inner peripheralface 107a in the portion having no hub stop rib 107d of the smallcylindrical portion 107 (or since there is no contact enough to generatebig frictional resistance between the outer peripheral face 110f and theinner peripheral face 107a excluding the hub stop rib 107d in case whereno gap space 149 is formed.), the hub 109 is smoothly inserted into thehole space 104a of the small cylindrical portion 107.

At the position where the main pillar portion 110 of the hub 109 iscompletely inserted into the hub insertion hole 104b, the small pillarportion 111 is inserted into the hole 108a so as to penetrate it.

The positional relation between the hub stop rib 107d of the hubinsertion portion 104 and the hub stop groove 110c of the hub 109 isformed as the main pillar portion 110 is completely inserted into thehub insertion hole 104b, and at the same time, each of them is at theposition corresponding to and adjusting to each other, and both areengaged with each other such that the seal portions 107e, 107e of thehub stop rib 107d and the opening ends 110e, 110e of the hub stop groove110c are respectively abutted on each other abutting on each other.

As explained heretofore, insertion of the hub 109 into the syringe body102 finishes.

The hub 109, after insertion, exists in such a manner that the sphericalface 131c side of the insertion portion 131b of the hub engagementportion 131 of the piston 123 is contacted with the wall face 117afacing the introducing portion 117 of the piston engagement hole 115provided with the hub 109.

The insertion operation of the hub 109 into the syringe body 102 can beexecuted only by pressing the hub 109, and therefore, it is easy with nocomplex assembly operation.

Subsequently, the needle 121 is inserted into the needle insertion hole112 of the hub 109 so as to be bonded. That is, the needle 121 isinserted into the needle insertion hole 112 from the rear end side ofthe needle 121 in the direction as shown by the arrow XB, as shown inFIG. 7 or FIG. 8, till the rear end abuts on the innermost wall face110d of the hub 109 of the needle insertion hole 112. After insertion,the space between the hub 109 and the needle 121 in the needle insertionhole 112 is filled with the adhesive 122, and the adhesive 122 ishardened, after that the insertion of the needle 121 to the hub 109finishes. Since the needle insertion hole 112 has portions taperinglyformed, which inside diameter is made reduced for the direction as shownby the arrow XB, the adhesive 122 flows to innermost end of the arrow XBside of the needle insertion hole 112, so the filling with the adhesive122 is certainly executed. Insertion and attachment of the needle 121means end of assembly of the syringe assembly 101.

As described heretofore, the assembly of the syringe assembly 101 iseasy with no complex operation since the most operations (that is, allthe operations excluding the operation of inserting and fixing theneedle 121) are executed by pressing. In addition, since the hub 109 isinserted after the piston 123 is inserted into the syringe body 102,dust entry into the inside space 102a is extremely prevented in case ofinsertion of the hub 109.

The assembly above-mentioned may be executed in such a manner that theneedle 121 is inserted into the hub 109 in advance, and in theafore-mentioned state, the hub 109 inserted the needle 121 therein isinserted into the syringe body 102.

The syringe assembly 101 assembled as shown before, is used and, afterthat, the syringe assembly 101 is discarded as follows.

At first, the needle 121 of the syringe assembly 101 is advanced into aninjection medium 152 in a medicine bottle (not shown), the piston 123 ispulled in the direction as shown by the arrow XB with respect to thesyringe body 102, and by differential pressure, the injection medium 152in the medicine bottle is flowed to a medium holding space 153 which isa space on the needle 121 side rather than the piston 123 of the holespace 104a and inside space 102a of the syringe body 102 on the righthand of FIG. 7 from the hub 109 of the hub insertion portion 104 passingthrough the medium flow hole 121a of the needle 121, the flow hole 113of the hub 109 and the piston engagement hole 115 so as to fill thesyringe assembly 101.

In case of filling with the injection medium 152, a differentialpressure force in the direction as shown by the arrow XB by differentialpressure between the outside and the medium holding space 153 acts onthe hub 109. However, restoring force in the direction as shown by thearrow XD which the hub insertion portion 104 has is set in such apredetermined size as described heretofore, thereby seal pressures XF1respectively act between each seal portion 107e and each opening end110e on the arrow XA side and the arrow XB side between the hub 109 andthe hub insertion hole 104 against the maximum differential pressureforce predicted, and then sealing between the hub stop rib 107d and thehub 109 is not disengaged.

After filling with the injection medium 152, the needle 121 of thesyringe assembly 101 is stuck into an injection portion of a patient.

Subsequently, the outer press plate 127 of the piston 123 is pressed inthe direction as shown by the arrow XA so as to drive the piston 123with respect to the syringe body 102 in the direction as shown by thearrow XA. The injection medium 152 of the medium holding space 153 ispressurized so as to flow into the body in the injection portion of apatient through the piston engagement hole 115 of the hub 109, the flowhole 113, the medium flow hole 121a of the needle 21.

On this occasion, the injection medium 152 is pressurized and an actionforce by the pressure of the injection medium 152 is added to the hub109 in the direction as shown by the arrow XA from the end face 110bside of the hub 109 adjacent to the injection medium 152. However, therestoring force in the direction as shown by the arrow XD which the hubinsertion portion 104 has is set in such a predetermined size, therebyseal pressures XF1 respectively act between each seal portion 107e andeach opening end 110e on the arrow XA side and the arrow XB side betweenthe hub 109 and the hub insertion hole 104 against the maximum actionforce predicted, and then sealing between the hub stop rib 107d and thehub 109 is not disengaged.

After a predetermined amount of the injection medium 152 is flowed intothe body in the injection portion of a patient, that is, after the taper135b of the packing 133 is inserted into the inside of the taper 106 ofthe syringe body 102 so as to adjust into it, and as shown in FIG. 7,the piston 123 is driven until the insertion portion 131b of the hubengagement portion 131 of the piston 123 abuts on the wall face 117a inthe introducing hole 117 of the piston engagement hole 115 of the hub109, the whole syringe assembly 101 is pulled in the direction as shownby the arrow XB to a patient, and the needle 121 is pulled out of theinjection portion of a patient.

After the needle 121 is pulled out, the operation of storing the needleis executed as follows.

In the operation of storing the needle, an engagement operation betweenthe piston 123 and the hub 109 is executed as follows.

That is, the outer press plate 127 of the piston 123 is further pressedwith fingers in the direction as shown by the arrow XA, and while thepacking 133 is elastically reduced by pressing it to the taper 106 ofthe syringe body 102, the insertion pillar portion 130b of the packingsupport 130 and the hub engagement portion 131 are pressed and moved inthe hub insertion hole 104b in the direction as shown by the arrow XA,and then the insertion portion 131b of the hub engagement portion 131 ispressed and moved from the introducing portion 117 of the pistonengagement hole 115 for the engagement holding portion 116 in thedirection as shown by the arrow XA.

That is, the piston 123 is pressed and moved in the direction as shownby the arrow XA, thereby the insertion portion 131b is pressed to thewall face 117a in the introducing portion 117. However, the arrow XAside of the insertion portion 131b is the spherical face 131c, and thenthe insertion portion 131b is formed in such a manner that the sectionperpendicular to the axis center XP1 is reduced for the direction asshown by the arrow XA. Then, the insertion portion 131b is pressed tothe wall face 117a in this spherical face 131c. The inside of theintroducing portion 117 is taperingly formed reducing for the directionas shown by the arrow XA. Therefore, the insertion portion 131b ispressed in the introducing portion 117 in the direction as shown by thearrow XA, thereby stresses by pressing pressure respectively actingbetween the insertion portion 131b and the projection 120 forming thewall face 117a respectively effectively act, elastically recuding thecross section perpendicular to the axis center XP1 for the insertionportion 131b, elastically enlarging the inside of the introducingportion 117 in the direction as shown by the arrow XC for the projection120. As the result, the cross section perpendicular to the axis centerXP1 of the insertion portion 131b is reduced, and the inside of theintroducing portion 117 is enlarged in the direction as shown by thearrow XC, thereby the insertion portion 131b being pressed in thedirection as shown by the arrow XA is moved in the introducing portion117 in the direction as shown by the arrow XA.

As shown in FIG. 7, just before the start of the operation of storing aneedle, the hole space 104a between the end face 110b of the hub 109 andthe insertion pillar portion 130b of the piston 123 side (that is, themedium holding space 153) is filled with the remaining injection medium152. The operation of storing the needle starts and the piston 123 ispressed and moved in the direction as shown by the arrow XA as describedbefore, thereby the remaining injection medium 152 is pressurized.However, a plurality of grooves 132 are provided with the insertionportion 131b as described heretofore, these grooves 132 are not closedwhen the insertion portion 131b and the wall face 117a are abutted oneach other by pressing. Therefore, when the insertion portion 131b andthe wall face 117a are abutted on each other by pressing, the hole space104a side and the engagement holding portion 116 side communicate withthe grooves 132, and the remaining injection medium 152 pressurized inthe hole space 104a flows to the engagement holding portion 116 sidethrough the grooves 132, and then, is expelled outside through the flowhole 113 and the medium flow hole 121a of the needle 121. That is, whenthe operation of storing the needle starts and the piston 123 is pressedand moved in the direction as shown by the arrow XA, the remaininginjection medium 152 pressurized in the hole space 104a is adequatelyexpelled outside and the pressure is not extremely increased. Therefore,resistance by pressure of the remaining injection medium 152 is notextremely acted on the piston 123 and then the piston 123 is pressed andmoved in the direction as shown by the arrow XA with an extremely smallforce.

The piston 123 is further pressed in the direction as shown by the arrowXA so as to further move the insertion portion 131b into the introducingportion 117 in the direction as shown by the arrow XA. That is, theinsertion portion 131b is moved from the arrow XA side thereof to theengagement holding portion 116 side passing through the boundary portion119 between the introducing portion 117 and the engagement holdingportion 116, and the insertion portion 131b is completely inserted intothe engagement holding portion 116 as shown by the two-dot chain line ofFIG. 7, thereby the pressing of the piston 123 is stopped. The insertionportion 131b is completely inserted into the engagement holding portion116, thereby the hub engagement portion 131 and the piston engagementhole 115 are engaged with each other and then the operation of engagingthe piston 123 and the hub 109 with each other finishes.

A pressing pressure force in the direction as shown by the arrow XA actson the insertion portion 131b, thereby a pressing pressure force in thedirection as shown by the arrow XA acts on the hub 109 also. However,the hub 109 is supported or can be supported with the hand by which thesyringe body 102 is supported, through the hub stop rib 107 of the hubinsertion portion 104 or the end wall 108 in the direction as shown bythe arrow XB. Therefore, the hub 109 does not move in the direction asshown by the arrow XA and the like if receiving a pressing pressureforce, and the hub 109 is not pulled out of the hole 108a of the endwall 108 in the direction as shown by the arrow XA.

Subsequently, the piston 123 is pulled with a predetermined pullingforce against the syringe body 102 in the direction as shown by thearrow XB. That is, an action force in the direction as shown by thearrow XB by a predetermined pulling force acts on the piston 123 and theinsertion portion 131b of the hub engagement portion 131. The restoringforce in the direction as shown by the arrow XD which the hub insertionportion 104 has is set in such a predetermined size describedheretofore. Therefore, the seal between each seal portion 107e and eachopening end 110e of the arrows XA and XB sides between the hub 109 andthe hub insertion portion 104 is disengaged against the action force inthe direction as shown by the arrow XB by a predetermined pulling force,and then engagement between the hub stop rib 107d and the hub stopgroove 110c is disengaged. The engagement between the hub stop rib 107dand the hub stop groove 110c is disengaged and the hub 109 is furtheradvanced in the direction as shown by the arrow XB so as to be pulleduntil the hub 109 is completely pulled out of the hub insertion hole104b in the direction as shown by the arrow XB.

On this occasion, the insertion portion 131b of the hub engagementportion 131 inserted into the engagement holding portion 116 of thepiston engagement hole 115 is pressed for the wall face 116a of theengagement holding portion 116 in the direction as shown by the arrow XBby pulling in the direction as shown by the arrow XB, as describedbefore. However, the portion where the insertion portion 131b and thewall face 116a are abutted on each other by pressing is one of the endportion of the arrow XB side in the insertion portion 131b, that is, onewhich outside diameter is biggest. Besides, since the portion which theinsertion portion 131b abuts on is the base side, that is, the sidewhere the wall is thick, of the projection 120, the insertion portion131b and the projection 120 are in such a state that they are hard toelastically deformed for their constitution against the reactionreceiving in the portion where the insertion portion 131b and the wallface 116a are abutted on each other, from the wall face 116a side or theinsertion portion 131b side. Therefore, the insertion portion 131b isnot pulled outside of the engagement holding portion 116 by theabove-mentioned pulling in the direction as shown by the arrow XB. Then,the engagement between the piston 123 and the hub 109 is certainlymaintained.

When the hub 109 is pulled out, since the gap space 149 is formedbetween the outer peripheral face 110f of the main pillar portion 110 ofthe hub 109 and the inner peripheral face 107a of the portions having nohub stop rib 107d of the small cylindrical portion 107 (or since thereis no contact enough to generate big frictional resistance between theouter peripheral face 110f and the inner peripheral face 107a excludingthe hub stop rib 107d if no gap space 149 is formed), the pullingoperation can be executed with a small force after the engagementbetween the hub stop rib 107d and the hub stop groove 110c isdisengaged.

The piston 123 is further pulled in the direction as shown by the arrowXB in such a manner that the needle 121 inserted and fixed on the arrowXA side of the hub 109 is inserted into the hub insertion hole 104b inthe direction as shown by the arrow XB from the hole 108a of the endwall 108 and further inserted into the inside space 102a of the maincylindrical portion 103 in the direction as shown by the arrow XB, andthe top end of the needle 121 is completely inserted into the insidespace 102a.

The piston 123 is further pulled until the inner press plate 129 abutson the engagement rib 103b of the main cylindrical portion 103 of thesyringe body 102, and then the piston 123 is stopped.

Then, as shown in FIG. 11, the notch 126 of the piston body 125 ispositioned near the opening end 103a of the syringe body 102.Subsequently, a force in the direction as shown by the arrow XC is givento the piston 123. A force in the direction as shown by the arrow XC isadded to the piston 123 with respect to the syringe body 102, therebythe piston body 125 is bent in the notch 126 which structure isrelatively weak against bending stress in the piston body 125, and thepiston body 125 is divided into the arrow XA side portion and the arrowXB side portion forming a boundary by the notch 126.

Since the inner press plate 129 is abutted on the engagement rib 103band stopped, a force in the direction as shown by the arrow XC added tothe piston 123 is effectively acting on the notch 126 of the piston body125 with the portion where the inner press plate 129 and the engagementrib 103b are abutted on each other as its supporting point when thepiston body 125 is bent and taken, applying a principle of lever.Therefore, the piston 125 can be easily bent and taken.

Subsequently, the portion of the syringe body 102 side bent and takenand the portion of the outer press plate 127 of the piston 123 aredisposed of so as to be discarded. Since the needle 121 is completelyinserted and stored in the inside space 102a of the syringe body 102being held with the top end portion of the piston 123 remaining in theinside space, there is no fear of hurting hands or the like and beingsecondarily infected from a wound by the needle 121. Therefore, wastedisposal can be safely executed. As described before, the operation ofstoring the needle finishes and the use of the syringe assembly 101 andwaste disposal after use all finish.

In the syringe assembly 101 explained in the above-mentioned embodiment,the slits 150 are formed at the sringe X100. However, no slit 150 may beformed at the syringe X100 of the syringe assembly 101.

In case where the syringe assembly 101 having no slit 150 at the syringeX100 is assembled, when the hub 109 is inserted into the hub insertionhole 104b, in first, the hub 109 is inserted into the inside space 102afrom the opening end 103a side of the syringe X100, and thereafter thehub 109 is inserted into the hub insertion hole 104b through the insidespace 102a.

The seal portion of the hub 109 explained in the above-mentionedembodiment, is a groove, that is, the hub stop groove 110c. However, anyform of the seal portion is available as long as the seal portion isannularly formed on the outer peripheral face 110f side of the hub body190, capable of engaging with the inner face of the hub insertion hole104b.

For instance, as shown in FIG. 12 or FIG. 13, the seal portion may be inthe shape of a projection, that is, a seal rib 157.

That is, in the embodiment as shown in FIG. 12, the seal rib 157annularly formed is provided on the outer peripheral face 110f side ofthe main pillar portion 110 of the hub 109 in place of the hub stopgroove 110c in the above-mentioned embodiment. In the syringe X100 usedwith the hub 109 provided the seal rib 157 therewith, the hub sealportion of the inner face side of the hub insertion hole 104b isprovided as an annular seal groove 159 capable of engaging with the sealrib 157, in place of the hub stop rib 107d in the above-mentionedembodiment.

In the embodiment as shown in FIG. 13, the seal rib 157 annularly formedis provided on the outer peripheral face 110f side of the main pillarportion 110 of the hub 109 in place of the hub stop groove 110c in theabove-mentioned embodiment. In the syringe X100 used with the hub 109provided the seal rib 157 therewith, the hub seal portion of the innerface side of the hub insertion hole 104b is formed on the same plane asthe inner peripheral face 107a. That is, the seal rib 157 engages withthe inner peripheral face 107a which is the hub seal portion of theinner face side of the hub insertion hole 104b, so as to generate africtional force in the directions as shown by the arrows XA and XB inthe figure by pressing the inner peripheral face 107a in the directionsas shown by the arrow XC in the figure.

The seal portion of the hub 109 explained in the above-mentionedembodiment can be formed in the shape of a projection, that is, a foldportion 161, as shown in FIG. 14.

That is, in the embodiment as shown in FIG. 14, the main pillar portion110 of the hub 109 is imaginarily comprised by a plurality of mainpillar portion pieces 160 (The number is 5 in FIG. 14) in the shape of ataper which outside diameter is more reduced for the direction as shownby the arrow XB of the direction of the axis center XP1 of the mainpillar portion 110, and a plurality of main pillar portion pieces 160are formed unitedly arranging in a line in the directions as shown bythe arrows XA and XB. That is, a plurality of fold portions 161 in theshape of a projection, formed by a plurality of the main pillar portionpieces 160, are annularly provided on the outer peripheral face 110fside of the main pillar portion 110 of the hub 109.

Therefore, the main pillar portion 110 of the hub 109 is inserted intothe hub insertion hole 104b, thereby a plurality of the fold portions161 of the main cylindrical portion 110 engages and contacts with theinner peripheral face 107a of the hub insertion hole 104b with apredetermined seal pressure XF1.

The main pillar portion 110 is inserted into the hub insertion hole 104bin the direction as shown by the arrow XB from the hole 108a of the endwall 108. In case of insertion, since the fold portion 161 is taperinglyformed in the direction as shown by the arrow XB, the hub 109 can besmoothly inserted into the hub insertion hole 104b for its constitution.Since the main pillar portion 110 is easily inserted into the hubinsertion hole 104b by the fold portions 161 in the shape of a taper, itis also applied to the syringe body 102 having no slit 150 in the hubinsertion hole 104b, as well as the syringe body 102 having the slits150 in the hub insertion hole 104b.

In the above-mentioned embodiment, the first bypass means of the hubengagement portion 131 is provided as the groove 132 provided with theinsertion portion 131b. However, any form of the first bypass means isavailable as long as the first bypass means is provided such that thepiston engagement hole 115 of the hub 109 and the medium holding space153 of the inside of the syringe X100 communicate with each other whenthe hub engagement portion 131 is abutted on the hub 109. For instance,as shown in FIG. 15, an opening 139a is formed at the top of theinsertion portion 131b facing the piston engagement hole 115 of the hubengagement portion 131 (that is, the end portion of the arrow XA side),and the other plurality of openings 139b are formed on the outerperipheral face side of the pillar portion 131a of the hub engagementportion 131, and a bypass hole 139 is formed extending the insertionportion 131b and the pillar portion 131a communicating the opening 139aof the insertion portion 131b side and the opening 139b of the pillarportion 131a side with each other, and then this bypass hole 139 may bethe first bypass means.

In the above-mentioned embodiment, even when the hub engagement portion131 is abutted on the hub 109, the first bypass means is provided withthe hub engagement portion 131 in order to communicate the pistonengagement hole 115 and the medium holding space 153 of the syringe X100with each other. However, in place of the first bypass means, the secondbypass means, communicating a communicating space communicating with themedium flow hole 121a of the needle 121, such as the flow hole 113 ofthe hub 109 and the medium holding space 153 of the inside of thesyringe X100 with each other, that is, communicating the pistonengagement hole 115 and the medium holding space 153 with each other,can be formed on the hub 109 side.

For instance, as shown in FIG. 16, the second bypass means may be formedas a plurality of hub bypass grooves 140 formed along the wall face 117afacing the introducing hole 117 of the piston engagement hole 115,communicating the engagement holding portion 116 and the opening 117b ofthe introducing hole 117. In case where the hub bypass grooves 140 areformed at the wall face 117a, the piston engagement hole 115 and themedium holding space 153 of the syringe X100 communicate with each otherthrough the hub bypass grooves 140 also when the hub engagement portion131 and the hub 109 are abutted on each other.

As shown in FIG. 17, the second bypass means formed in place of thefirst bypass means may be a hub bypass hole 141 which is a hole providedpenetrating the hub body 190 between the wall face 116a of theengagement holding portion 116 and the outer peripheral face 110f of thehub 109.

The hub bypass hole 141 may be a hole provided penetrating the hub body109 between the flow hole 113 and the outside of the hub 109.

Another embodiment of the present invention will now be describedhereinafter.

A syringe assembly 201 according to the present invention has a syringeY100 made of resin, as shown in FIG. 19. A syringe body 202 is providedwith the syringe Y100 (FIG. 19 is a typical cross section of the syringeassembly 201, but its side is shown in a part of a piston 223, describedhereinafter, not the section, for convenience.). A main cylindricalportion 203, cylindrically formed, is provided with the syringe body202. A direction of an axis center of the main cylindrical portion 203,that is, the reciprocating directions parallel to an axis center YQ1 arean arrow YA direction in the figure (or the left direction of the paperof FIG. 18.) and an arrow YB direction (or the right direction of thepaper of FIG. 18).

On the outer periphery side of the main cylindrical portion 203, asyringe support 205 is provided near an opening end 203a of the arrow YBside of the main cylindrical portion 203 (the right side of the paper ofFIG. 18), in such a manner as forming a flange of the main cylindricalportion 203. On an inner peripheral face 203c side of the maincylindrical portion 203, an engagement rib 203b, projecting in thedirection for the axis center YQ1 of the main cylindrical portion 203,that is, the direction as shown by the arrow YD in the figure, isannularly formed near the opening end 203a along the inner peripheralface 203c.

On the arrow YA side of the main cylindrical portion 203 (the left sideof the paper of FIG. 19) a taper 206 in the shape of a funnel, whichinside diameter is reduced at a predetermined rate of K1 for thedirection as shown by the arrow YA, is formed unitedly connecting withthe main cylindrical portion 203.

The inside of the main cylindrical portion 203 and the inside of thetaper 206 communicate with each other in the directions as shown by thearrows YA and YB, and the space combining both insides is an insidespace 202a of the syringe body 202.

On the side of the arrow YA of the taper 206, that is, on the side ofthe top of the syringe body 202, as shown in FIG. 18 or FIG. 19, a hubinsertion portion 204 is formed unitedly connecting with the taper 206,and the hub insertion portion 204 has a small cylindrical portion 207.The small cylindrical portion 207 is formed unitedly connecting with thetaper 206, and coaxial with the main cylindrical portion 203, and theinside diameter of the small cylindrical portion 207 is smaller than oneof the main cylindrical portion 203.

An inner peripheral face 207a side of the small cylindrical portion 207is a hub insertion hole 204b. A hub stop rib 207d projecting for theaxis center YQ1 is formed in the hub insertion hole 204b. The hub stoprib 207d is annularly formed along the inner peripheral face 207a of thesmall cylindrical portion 207. The section of a plane including the axiscenter YQ1 of the hub stop rib 207d (that is, the section as shown inFIG. 18) is a circular arc.

On the other hand, on an outer peripheral face 207f side of the smallcylindrical portion 207, a stiffening rib 207c is annularly provided atthe position corresponding to the hub stop rib 207d putting the smallcylindrical portion 207 therebetween.

As shown in FIG. 19 through FIG. 21, an end wall 208 formed in the shapeof a circular plate, which outside diameter is equal to one of the smallcylindrical portion 207, is provided with the small cylindrical portion207. The end wall 208 is provided united with the small cylindricalportion 207 contacting a wall face 208b of the arrow YB side of the endwall 208 and an end portion 207b of the arrow YA side of the smallcylindrical portion 207 with each other. A hole 208a having a circularsection, penetrating both front and back wall faces of the end wall 208in the directions as shown by the arrows YA and YB, is provided with theend wall 208, with the axis center YQ1 as its center. The arrow A sideof the hole 208a is taperingly formed enlarging the sectional insidediameter in the direction as shown by the arrow YA.

As shown in FIG. 20 or FIG. 21, three slits 250 are formed extending onthe end wall 208 and the small cylindrical portion 207. The slits 250are formed extending in the end wall 208 in a radial direction withrespect to the axis center YQ1, that is, in the directions as shown bythe arrows YC and YD in the figure (The arrow YC direction is oppositeto the arrow YD direction), communicating with the hole 208a provided inthe end wall 208, and parallel to the directions as shown by the arrowsYA and YB in the small cylindrical portion 207. The slits 250 are formedat the positions on the arrow YA side rather than the hub stop rib 207dand the stiffening rib 207c, and not reaching the hub stop rib 207d andthe stiffening rib 207c.

Since the arrow YA side of the hub insertion portion 204 is divided intothree parts by the slits 250, the portions of the hub insertion portion204 formed the slits 250 are easy to be elastically enlarged in thedirection as shown by the arrow YC. That is, when the syringe assembly201 is assembled by inserting a hub 209 described hereinafter into thesyringe Y100, the portions of the hub insertion portion 204 formed theslits 250 are elastically enlarged in the direction as shown by thearrow YC and the hole 208a of the end wall 208 is enlarged, thereby thehub 209 referred hereinafter can be inserted into the hub insertion hole204b through the hole 208a.

The hub insertion portion 204 is comprised as explained heretofore. Thesyringe Y100 is comprised of the syringe support 205, the maincylindrical portion 203 comprising the syringe body 202, the taper 206,and the hub insertion portion 204 in such a manner that these areunited.

The hub 209 made of resin, which is harder than the syringe Y100, isprovided with the hub insertion hole 204b of the hub insertion portion204. As shown in FIG. 18 through FIG. 20, the hub 209 has a hub body290. A main pillar portion 210, which longitudinal direction is parallelto the directions as shown by the arrows YA and YB, which axis center isthe axis center YQ1, is provided in the shape of a cylinder with the hubbody 290.

A hub stop groove 210c is formed on the side of an outer peripheral face210f of the main pillar portion 210. The hub stop groove 210c isannularly formed along the outer peripheral side of the main pillarportion 210.

On an end face 210a side of the arrow YA side of the main pillar portion210, a small pillar portion 211 is provided extending in the directionsas shown by the arrows YA and YB directions, coaxial with and unitedwith the main pillar portion 210. The hub 209 is provided such that themain pillar portion 210 of the hub 209 is inserted into the hubinsertion hole 204b of the hub insertion portion 204, and the smallpillar portion 211 of the hub 209 is inserted into the hole 208a of theend wall 208 so as to penetrate. The hub stop rib 207d of the hubinsertion portion 204 and the hub stop groove 210c of the hub 209 are atthe positions corresponding to and adjusting to each other, and then thehub stop rib 207d is engaged with the hub stop groove 210c inserting thetop end side on the arrow YD side thereof into the hub stop groove 210cwhich is at the position corresponding and adjusting to one of the hubstop rib 207d.

Since the width of the hub stop rib 207d in the directions as shown bythe arrows YA and YB is broader than one of the hub stop groove 210c inthe directions as shown by the arrows YA and YB, the hub stop rib 207dis engaged with the hub stop groove 210c abutting on opening ends 210e,210e of both sides of the arrows YA and YB of the hub stop groove 210cin seal portions 207e, 207e on the sides of the arrows YA and YB of thetop thereof.

The inner peripheral face 207a of the small cylindrical portion 207 isnot in contact with the outer peripheral face 210f of the hub 209 in theportions excluding the hub stop rib 207d, and a gap space 249 is formedbetween the inner peripheral face 207a and the outer peripheral face210f. That is, since contact between the inner peripheral face 207a sideof the hub insertion portion 204b and the hub 209 is executed onlybetween the hub stop rib 207d and the outer peripheral face 210f side ofthe hub 209, when the syringe assembly 201 is assembled by inserting thehub 209 into the syringe Y100, the hub 209 can be easily inserted intothe hub insertion portion 204. In addition, in case of the operation ofstoring a needle, described hereinafter, the hub 209 is easily pulledout of the hub insertion portion 204 (As long as insertion of the hub209 into the hub insertion portion 204 and pulling of the hub 209 out ofthe hub insertion portion 204 can be easily executed, the portionsexcluding the hub stop rib 207d of the inner peripheral face 207a of thesmall cylindrical portion 207 may be in contact with the outerperipheral face 210f of the hub 209.).

An end face 210b of the arrow YB side of the main pillar portion 210 ofthe hub 209 is positioned on the arrow YA side rather than the boundarybetween the hub insertion hole 204b and the inside space 202a (that is,the boundary between the inside of the small cylindrical portion 207 andthe inside of the taper 206), and the space of the inside of the hubinsertion hole 204b on the arrow YB side rather than the end face 210bis a hole space 204a.

On the other hand, the hub insertion portion 204 is elastically deformedexpanding the small cylindrical portion 207 in the direction as shown bythe arrow YC in such a state that the hub 209 is provided with the hubinsertion hole 204b. That is, the restoring force by elastic deformationof the small cylindrical portion 207 is transferred to the hub 209through the hub stop rib 207d of the small cylindrical portion 207. Thatis, predetermined seal pressures by the restoring force respectively actbetween the hub stop rib 207d and the hub 209 in the portions betweenthe seal portion 207e and the opening end 210e of the hub stop groove210c in which both abut on each other, and then, the portion between theseal portion 207e and the opening end 210e is in a water tight state oran air tight state.

The rigidity of the hub stop rib 207d and the portion near thereof isincreased in the small cylindrical portion 207 by the stiffening rib207c which is at the position corresponding to the hub stop rib 207dputting the small cylindrical portion 207 therebetween, and then apredetermined restoring force by elastic deformation of the smallcylindrical portion 207 can be effectively obtained.

As shown in FIG. 18 through FIG. 20, a needle insertion hole 212 isprovided with the hub 209. The needle insertion hole 212 is providedforming a circular opening 212a, which center is the axis center YQ1, atan end face 211a of the arrow YA side of the small pillar portion 211 ofthe hub 209, extending from the end face 211a in the direction as shownby the arrow YB. An end portion 212b of the arrow YB side of the needleinsertion hole 212 reaches the inside of the main pillar portion 210 andthe end portion 212b is in contact with a wall face 210d of the mainpillar portion 210. In the needle insertion hole 212, tapers areadequately formed such that the diameter of the needle insertion hole212 is made narrower for the direction as shown by the arrow YB.

On the other hand, a flow hole 213 is provided with the main pillarportion 210 of the hub 209 adjacent to the arrow YB side of the needleinsertion hole 212 (right side of the paper of FIG. 18). The flow hole213 is cylindrically formed such that its center is the axis center YQ1and its diameter is smaller than one of the end portion 212b of theneedle insertion hole 212. The flow hole 213 is provided forming acircular opening at the wall face 210d of the main pillar portion 210,communicating with the needle insertion hole 212.

A piston engagement hole 215, which section perpendicular to the axiscenter YQ1 is a circle, is provided with the main pillar portion 210 ofthe hub 209 communicating with and adjacent to the arrow YB side of theflow hole 213, coaxial with the axis center YQ1. The arrow YB side ofthe piston engagement hole 215 is open outside in the end face 210b ofthe main pillar portion 210.

The piston engagement hole 215 is comprised of two parts, an engagementholding portion 216 of the arrow YA side and an introducing portion 217of the arrow YB side. The engagement holding portion 216 is almostcylindrical shape, coaxial with the axis center YQ1, and both endportion sides of the arrows YA and YB thereof are taperingly formed suchthat each diameter is made narrower for the direction as shown by thearrow YA or arrow YB. The end portion side of the arrow YA side of theengagement holding portion 216 is communicated and connected with theflow hole 213.

The introducing portion 217 communicates with and is adjacent to the endportion of the arrow YB side of the engagement holding portion 216. Thediameter of the introducing portion 217 is made bigger for the directionas shown by the arrow YB. Then, the portion sandwitched between a wallface 216a facing the engagement holding portion 216 and a wall face 217afacing the introducing portion 217 of the main pillar portion 210 formsa projection 220 projecting for the axis center YQ1 with a boundaryportion 219 between the engagement holding portion 216 and theintroducing portion 217 as an apex.

On the other hand, as shown in FIG. 19 or FIG. 20, a needle 221 isinserted into the needle insertion hole 212 of the hub 209. The needle221 is inserted into the needle insertion hole 212 from the rear endportion thereof and the top end side is positioned outside of thesyringe body 202. The rear end of the needle 221 abuts on the wall face210d formed on the arrow YB side of the needle insertion hole 212. Amedium flow hole 221a provided penetrating from the top end to the rearend side of the needle 221 and the flow hole 213 are adjacent to andcommunicate with each other in the directions as shown by the arrows YAand YB.

An adhesive 222 is injected into the needle insertion hole 212 fillingbetween the needle 221 and the hub 209 and is hardened.

The piston 223 is provided with the syringe assembly 201, as shown inFIG. 18 or FIG. 19 (FIG. 19 is a typical sectional view of the syringeassembly 201, but with respect to a piston body 225, an outer pressplate 227, an inner press plate 229, a packing support 230, a hubengagement portion 231, referred hereinafter, of the piston 223, theirsides are shown, not their sections, for convenience.)

The piston 223 has the bar-shaped piston body 225 extending in thedirections as shown by the arrows YA and YB. The piston body 225 iscomprised such that two congruent plate portions 225a, each which is aplate shaped rectangle especially long in the directions as shown by thearrows YA and YB, are unitedly cross provided with each other such thatthe sections thereof form the shape of a cross. The width perpendicularto the directions as shown by the arrows YA and YB of the plate face ofthe plate portion 225a is almost equal to the inside diameter in theengagement rib 203b of the main cylindrical portion 203, and the pistonbody 225 is inserted into the main cylindrical portion 203 through theopening end 203a from the arrow YA side of the piston body 225.

On each plate portion 225a of the piston body 225, notches 226 areformed from both side portions of the respective plate portions 225a,225a in the direction of the axis center (that is, the axis center YQ1)of the piston body 225 in the shape of a wedge near the direction by thearrow YA. Four notches 226 are provided at the positions adjusted oneanother in the directions as shown by the arrows YA and YB.

The outer press plate 227 in the shape of a circular plate, which plateface is perpendicular to the directions as shown by the arrows YA andYB, is provided united with the piston body 225 on the end portion sideof the arrow YB side of the piston body 225.

The inner press plate 229 in the shape of a circular plate, which plateface is perpendicular to the directions as shown by the arrows YA andYB, is provided united and coaxial with the piston body 225 on the endportion side of the arrow YA side of the piston body 225 (Therefore, theinner press plate 229 is positioned inside of the main cylindricalportion 203.), and the diameter of the inner press plate 229 is almostequal to the inside diameter of the main cylindrical portion 203(Therefore, the diameter of the inner press plate 229 is bigger than theinside diameter in the engagement rib 203b of the main cylindricalportion 203.).

As shown in FIG. 19, the packing support 230 is provided with the innerpress plate 229 on the arrow YA side thereof. A pillar portion 230a inthe shape of a cylinder, extending in the directions as shown by thearrows YA and YB, is provided with the packing support 230, beingcoaxial with the inner press plate 229. The diameter of the pillarportion 230a is smaller than one of the inner press plate 229. Thepillar portion 230a is provided on the arrow YA side of the inner pressplate 229, being united with the inner press plate 229. As shown in FIG.18 or FIG. 19, an insertion pillar portion 230b in the shape of acylinder, extending in the directions as shown by the arrows YA and YBbeing coaxial with the pillar portion 230a, having an outside diameteralmost equal to the inside diameter of the small cylindrical portion207, is provided on the arrow YA side of the pillar portion 230a, beingunited with the pillar portion 230a.

The hub engagement portion 231 is provided on the arrow YA side of theinsertion pillar portion 230b. A pillar portion 231a in the shape of acylinder, extending in the directions as shown by the arrows YA and YB,is provided with the hub engagement portion 231, being coaxial with theinsertion pillar portion 230b. The diameter of the pillar portion 231ais smaller than one of the insertion pillar portion 230b. The pillarportion 231a is provided on the arrow YA side of the insertion pillarportion 230b, being united with the insertion pillar portion 230b. Aninsertion portion 231b in the shape of a hemi-sphere, which diameter isbigger than one of the pillar portion 231a, is provided on the arrow YAside of the pillar portion 231a, being united with the pillar portion231a facing a spherical face 231c side to the arrow YA side. A pluralityof grooves 232 in the shape of a stripe are provided with the insertionportion 231b, being parallel to the spherical face 231c, extending fromthe top portion of the arrow YA side to the arrow YB side.

The diameter of the pillar portion 231a is almost equal to the insidediameter in the boundary portion 219 of the piston engagement hole 215provided with the hub 209. Therefore, the diameter of the insertionportion 231b is bigger than one of the boundary portion 219. The size ofthe insertion portion 231b allows itself to be sufficiently insertedinto and to be held by the engagement holding portion 216 of the pistonengagement hole 215.

on the other hand, as shown in FIG. 18, a packing 233 made of flexibleresin, is supported with the packing support 230. The packing 233 has apacking body 235 which is inserted inside of the main cylindricalportion 203 of the syringe Y100 so as to adjust. An engagement hole 235apenetrating the packing body 235 in the directions as shown by thearrows YA and YB is provided with the packing body 235. The pillarportion 230a of the packing support 230 and a part of the insertionpillar portion 230b penetrating the engagement hole 235a. That is, thepacking 233 engages with the packing support 230 such that the packingsupport 230 penetrates the engagement hole 235a, thereby the packing 233is supported by the packing support 230. The end portion of the arrow YBside of the packing body 235 abuts on the inner press plate 229 so as toeasily receive a force in the direction as shown by the arrow YA by theinner press plate 229.

The arrow YA side of the packing body 235 is a taper 235b. While theform of the inside of the taper 206 of the syringe body 202 is a taper,reducing the inside diameter at a predetermined rate K1 for thedirection as shown by the arrow YA, as described before, the form of thetaper 235b in a natural state is a taper, reducing the outside diameterat a predetermined rate K2, which is bigger than a predetermined rateK1. That is, the taper 235b is formed forming a remaining space 251between a surface 235e excluding the end portion 235d of the taper 235band the inner peripheral face 206a of the taper 206 when an end portion235d of the arrow YB side of the taper 235b in a natural state abuts onan inner peripheral face 206a of the taper 206 inside of the taper 206.

A part of the arrow YA side of the insertion pillar portion 230b of thepacking support 230 penetrating the engagement hole 235a furtherprojects on the arrow YA side rather than the taper 235b.

In such a state that the end portion 235d of the taper 235b is abuttedon the inside of the taper 206 of the syringe body 202 when the taper235b of the packing 233 is in a natural state, as shown in FIG. 18, theinsertion pillar portion 230b of the packing support 230 engaging withthe packing 233 is inserted into the hub insertion hole 204b of thesyringe body 202. The form of the packing 233 is set so as to make sucha state where the spherical face 231c of the insertion portion 231b ofthe hub engagement portion 231 contacts with the wall face 217a facingthe introducing portion 217 of the piston engagement hole 215.

The outside diameter of the packing body 235 of the packing 233 isalmost equal to one of the inner press plate 229. However, on the outerperipheral side of the packing body 235, annular folds 235c are doubleformed along the outer periphery of the packing body 235 arranging in aline in the directions as shown by the arrows YA and YB. Therefore, thepacking 233 is inserted into the main cylindrical portion 203 of thesyringe body 202, reducing the portion near the fold 235c of the packingbody 235 in the direction for the axis center YQ1, that is, in thedirection as shown by the arrow YD by elastic deformation. That is, thepacking 233 and the main cylindrical portion 203 are closely contactedwith each other in the folds 235c and the inner peripheral face 203c,and the portion between the packing 233 and the main cylindrical portion203 is sealed with water seal or air seal.

The inner peripheral face 203c of the main cylindrical portion 203 ofthe syringe body 202 is smoothly formed. Therefore, the piston 223inserted the packing 233 therein is free to slide in the inside space202a of the main cylindrical portion 203 in the directions as shown bythe arrows YA and YB.

The syringe assembly 201 is comprised as before, and then the syringeassembly 201 is used and, after that, the syringe assembly 201 isdiscarded as follows.

At first, the needle 221 of the syringe assembly 201 is advanced into aninjection medium 252 in a medicine bottle (not shown), the piston 223 ispulled in the direction as shown by the arrow YB with respect to thesyringe body 202, and by differential pressure, the injection medium 252in the medicine bottle is flowed to a medium holding space 253 on theneedle 221 side rather than the piston 223 of the hole space 204a of thehub insertion portion 204 and the inside space 202a of the syringe body202 passing through the medium flow hole 221a of the needle 221, theflow hole 213 of the hub 209 and the piston engagement hole 215 so as tofill the syringe assembly 201 with the injection medium 252.

In case of filling of the injection medium 252, a differential pressureforce in the direction as shown by the arrow YB by differential pressurebetween the outside and the medium holding space 253 acts on the hub209. However, the restoring force in the direction as shown by the arrowYD which the hub insertion portion 204 has is set as a predeterminedsize as described heretofore, thereby sealing between each seal portion207e and each opening end 210e of the arrow YA side and the arrow YBside is not disengaged between the hub insertion portion 204 and the hub209 against the maximum differential pressure force predicted.

After filling of the injection medium 252, the needle 221 of the syringeassembly 201 is stuck into an injection portion of a patient.

Subsequently, the outer press plate 227 of the piston 223 is pressed inthe direction as shown by the arrow YA so as to drive the piston 223with respect to the syringe body 202 in the direction as shown by thearrow YA. The injection medium 252 of the medium holding space 253 ispressurized so as to flow into the body in the injection portion of apatient through the piston engagement hole 215 of the hub 209, the flowhole 213, the medium flow hole 221a of the needle 221.

On this occasion, the injection medium 252 is pressurized and an actionforce by the pressure of the injection medium 252 is added to the hub209 in the direction as shown by the arrow YA from the end face 210bside of the hub 209 adjacent to the injection medium 252. However, therestoring force in the direction as shown by the arrow YD which the hubinsertion portion 204 has is set in such a predetermined size asdescribed heretofore, thereby sealing between each seal portion 207e andeach opening end 210e on the arrow YA side and the arrow YB side is notdisengaged between the hub insertion portion 204 and the hub 209 againstthe maximum action force predicted.

After a predetermined amount of the injection medium 252 is flowed intothe body in the injection portion of a patient, that is, after thepiston 223 is driven to the position where the end portion 235d of thetaper 235b of the packing 233 is abutted on the inside of the taper 206of the syringe body 202, and as shown in FIG. 18, the insertion portion231b of the hub engagement portion 231 of the piston 223 abuts on thewall face 217a in the introducing hole 217 of the piston engagement hole215 of the hub 209, that is, to an injection end position YP2 in thefigure, the whole syringe assembly 201 is pulled in the direction asshown by the arrow YB to a patient, and the needle 221 is pulled out ofthe injection portion of a patient.

After the needle 221 is pulled out, the operation of storing the needleis executed as follows.

In the operation of storing the needle, the engagement operation betweenthe piston 223 and the hub 209 is executed as follows.

That is, the outer press plate 227 of the piston 223 is further pressedwith fingers in the direction as shown by the arrow YA so as to pressthe piston body 225 in the direction as shown by the arrow YA, and thenthe insertion pillar portion 230b of the packing support 230 and the hubengagement portion 231 are fed in the direction as shown by the arrow YAin the hub insertion hole 204b.

Just before start of the operation of storing the needle, the piston 223is positioned such that the taper 235b in a natural state is positionedcorresponding to the inside of the taper 206, the end portion 235d ofthe arrow YB side of the taper 235b abuts on the inner peripheral face206a of the taper 206, and the remaining space 251 is formed between thesurface 235e excluding the end portion 235d of the taper 235b and theinner peripheral face 206a of the taper 206. Therefore, by pressingpressure in the direction as shown by the arrow YA of the piston body225, in the packing 233, the portion on the arrow YB side from theportion near the end portion 235d abutting on the taper 206 iscompressed in the directions as shown by the arrows YB and YD, and theother part is pressed out in the direction as shown by the arrow YAmaking use of the remaining space 251 in such a manner that the surface235e approaches the taper 206. Therefore, since the quantity of elasticcompression in the packing 233 is reduced by the remaining space 251,the piston 223 can be operated with extremely small force.

As shown in FIG. 18, just before start of the operation of storing theneedle, the hole space 204a between the end face 210b of the hub 209 andthe insertion pillar portion 230b of the piston 223 side (that is, themedium holding space 253) and the remaining space 251 (that is, themedium holding space 253) are filled with the remaining injection medium252. The operation of storing the needle is started, the piston 223 ispressed and moved in the direction as shown by the arrow YA as describedheretofore, thereby the remaining injection medium 252 is pressurized.However, a plurality of grooves 232 are provided with the insertionportion 231b, as described heretofore, and then these grooves 232 arenot occupied when the insertion portion 231b and the wall face 217a areabutted on each other by pressing. Therefore, when the insertion portion231b and the wall face 217a are abutted on each other by pressing, thehole space 204a or the remaining space 251 side and the engagementholding portion 216 side communicate with the grooves 232. The remaininginjection medium 252 pressurized of the hole space 204a or the remainingspace 251 flows to the engagement holding portion 216 side through thesegrooves 232 (This is because the injection medium 252 of the remainingspace 251 can flow to the hole space 204a side passing between theinsertion pillar portion 230b and the small cylindrical portion 207since the portion between the insertion pillar portion 230b and thesmall cylindrical portion 207 is not water tight.), and furthermore, isexpelled outside through the flow hole 213 and the medium flow hole 221aof the needle 221. That is, when the operation of storing the needlestarts and the piston 223 is pressed and moved in the direction as shownby the arrow YA, the remaining injection medium 252 pressurized in thehole space 204a or the remaining space 251 is appropriately expelledoutside, and the pressure is not extremely increased. Therefore, theresistance by pressure of remaining injection medium 252 is notextremely acted on the piston 223, and then the piston 223 is pressedand moved in the direction as shown by the arrow YA with extremely smallforce.

While the packing 233 is elastically reduced, the insertion pillarportion 230b of the packing support 230 and the hub engagement portion231 are pressed and moved in the direction as shown by the arrow YA inthe hub insertion portion 204b, and the insertion portion 231b of thehub engagement portion 231 is pressed and moved in the direction asshown by the arrow YA from the introducing portion 217 of the pistonengagement hole 215 for the engagement holding portion 216.

That is, the piston 223 is pressed and moved in the direction as shownby the arrow YA, thereby the insertion portion 231b is pressed to thewall face 217a in the introducing portion 217. However, the arrow YAside of the insertion portion 231b is the spherical face 231c, then theinsertion portion 231b is formed in such a manner that the sectionperpendicular to an axis center YP1 is reduced for the direction asshown by the arrow YA. Then, the insertion portion 231b is pressed tothe wall face 217a in this spherical face 231c. In addition, theintroducing portion 217 is taperingly formed reducing the inside thereoffor the direction as shown by the arrow YA. Therefore, the insertionportion 231b is pressed in the direction as shown by the arrow YA in theintroducing portion 217, thereby stress by pressing pressurerespectively acting between the insertion portion 231b and theprojection 220 forming the wall face 217a respectively effectively actsin such a manner that for the insertion portion 231b the cross sectionperpendicular to the axis center YP1 is elastically reduced, and for theprojection 220, the inside of the introducing portion 217 is elasticallyenlarged in the direction as shown by the arrow YC. As a result, thecross section perpendicular to the axis center YP1 of the insertionportion 231b is reduced and the inside of the introducing portion 217 isenlarged in the direction as shown by the arrow YC, thereby theinsertion portion 231b pressed in the direction as shown by the arrow YAmoves in the direction as shown by the arrow YA in the introducingportion 217.

Furthermore, the piston 223 is pressed in the direction as shown by thearrow YA so as to move the insertion portion 231b in the direction asshown by the arrow YA in the introducing portion 217. Therefore, theinsertion portion 231b is moved to the engagement holding portion 216side passing through the boundary portion 219 between the introducingportion 217 and the engagement holding portion 216 from the arrow YAside thereof, and the insertion portion 231b is completely inserted intothe engagement holding portion 216, thereby the pressing of the piston223 is stopped. The insertion portion 231b is completely inserted intothe engagement holding portion 216, thereby the hub engagement portion231 and the piston engagement hole 215 are engaged with each other, andthen the operation of engagement between the piston 223 and the hub 209finishes.

On this occasion, pressing pressure force in the direction as shown bythe arrow YA acts on the insertion portion 231b, thereby pressingpressure force in the direction as shown by the arrow YA also acts onthe hub 209. However, the hub 209 is supported or can be supported inthe direction as shown by the arrow YB with the hand supporting thesyringe body 202 through the hub stop rib 207d of the hub insertionportion 204 or the end wall 208. Therefore, the hub 209 is not almostmoved in the direction as shown by the arrow YA or the like if receivingpressing pressure force, and the hub 209 is not pulled out of the hole208a of the end wall 208 in the direction as shown by the arrow YA.

Subsequently, the piston 223 is pulled against the syringe body 202 inthe direction as shown by the arrow YB with a predetermined pullingforce. That is, an action force in the direction as shown by the arrowYB by a predetermined pulling force acts on the piston 223 and theinsertion portion 231b of the hub engagement portion 231. The restoringforce in the direction as shown by the arrow YD which the hub insertionportion 204 has is set in such a predetermined sized one, as describedheretofore, thereby the sealing between each seal portion 207e and eachopening end 210e on the arrow YA side and on the arrow YB side isdisengaged between the hub insertion portion 204 and the hub 209 againstthe action force in the direction as shown by the arrow YB by apredetermined pulling force. Therefore, the sealing between the hub stoprib 207d and the hub stop groove 210c is disengaged. The hub stop rib207d and the hub stop groove 210c are disengaged from each other and thehub 209 is further advanced in the direction as shown by the arrow YB,and then the hub 209 is pulled until it is completely pulled out of thehub insertion hole 204b in the direction as shown by the arrow YB.

On this occasion, since the gap space 249 is formed between the hub 209and the hub insertion hole 204b, contact between the hub 209 and thesmall cylindrical portion 207 is executed only through the hub stop rib207d portion, and the pulling operation can be easily executed with asmall force after the hub stop rib 207d and the hub stop groove 210c aredisengaged from each other.

The piston 223 is further pulled in the direction as shown by the arrowYB in such a manner that the needle 221 inserted and fixed on the arrowYA side of the hub 209 is inserted into the hub insertion hole 204b inthe direction as shown by the arrow YB from the hole 208a of the endwall 208 and further inserted into the inside space 202a of the maincylindrical portion 203 in the direction as shown by the arrow YB, andthe top end of the needle 221 is completely inserted into the insidespace 202a.

As shown in FIG. 22, the piston 223 is further pulled until the innerpress plate 229 abuts on the engagement rib 203b of the main cylindricalportion 203 of the syringe body 202, and then the piston 223 is stopped.

Then, the notch 226 of the piston body 225 is positioned near theopening end 203a of the syringe body 202. Subsequently, a force in thedirection as shown by the arrow YC is given to the piston 223. A forcein the direction as shown by the arrow YC is added on the piston 223with respect to the syringe body 202, thereby the piston body 225 isbent in the notch 226 which structure is relatively weak against bendingstress in the piston body 225, and the piston body 225 is divided intothe arrow YA side portion and the arrow YB side portion forming aboundary by the notch 226.

Subsequently, the portion of the syringe body 202 side bent and takenand the portion of the outer press plate 227 of the piston 223 aredisposed of so as to be discarded. Since the needle 221 is completelyinserted and stored in the inside space 202a of the syringe body 202being held with the top end portion of the piston 223 remaining in theinside space, there is no fear of hurting hands or the like and beingsecondarily infected from a wound by the needle 221. Therefore, wastedisposal can be safely executed. As described before, the operation ofstoring the needle finishes and the use of the syringe assembly 201 andwaste disposal after use all finish.

In the above-mentioned embodiment, the end portion 235d, capable ofabutting on the taper 206 by the movement of the packing 233 in thedirections as shown by the arrows YA and YB, that is, an engagementportion is formed at the packing 233. In addition, the surface 235e,that is, a pressing portion is formed such that the remaining space 251is formed between the surface 235e and the taper 206 when the endportion 235d and the taper 206 are abutted on each other. However, thesyringe assembly or the engagement portion of the packing 233 of thepiston according to the present invention may be formed in the formexcluding the end portion 235d.

For instance, as shown in FIG. 23, an engagement projection 255, capableof abutting on the taper 206 by movement of the packing 233 in thedirections as shown by the arrows YA and YB, is formed on a surface sideof the taper 235b of the packing 233, and then the engagement projection255 may become to be the engagement portion. The surface 235e excludingthe engagement projection 255 of the taper 235b becomes to be thepressing portion, and the remaining space 251 can be formed between thesurface 235e, that is, the pressing portion and the taper 206 when theengagement projection 255 and the taper 206 are abutted on each other.

A syringe assembly 201 according to the present invention has a syringeY100 made of resin, as shown in FIG. 25. A syringe body 202 is providedwith the syringe Y100 (FIG. 25 is a typical cross section of the syringeassembly 201, but a side is shown in a part of a piston 223, describedhereinafter, not the section, for convenience.). A main cylindricalportion 203, cylindrically formed, is provided with the syringe body202. A direction of an axis center of the main cylindrical portion 203,that is, the reciprocating directions parallel to an axis center YQ1 arean arrow YA direction in the figure (or the left direction of the paperof FIG. 25.) and an arrow YB direction (or the right direction of thepaper of FIG. 25).

On the outer periphery side of the main cylindrical portion 203, asyringe support 205 is provided near an opening end 203a of the arrow YBside of the main cylindrical portion 203 (the right side of the paper ofFIG. 25), in such a manner as forming a flange of the main cylindricalportion 203. On an inner peripheral face 203c side of the maincylindrical portion 203, an engagement rib 203b, projecting in thedirection for the axis center YQ1 of the main cylindrical portion 203,that is, the direction as shown by an arrow YD of the figure, isannularly formed near the opening end 203a along the inner peripheralface 203c.

On the arrow YA side of the main cylindrical portion 203 (the left sideof the paper of FIG. 25) a taper 206, which inside diameter is reducedat a predetermined rate of K1 for the direction as shown by the arrowYA, in the shape of a funnel, is formed unitedly connecting with themain cylindrical portion 203.

The inside of the main cylindrical portion 203 and the inside of thetaper 206 communicate with each other in the directions as shown by thearrows YA and YB, and the space combined both insides is an inside space202a of the syringe body 202.

On the side of the arrow YA of the taper 206, that is, on the side ofthe top of the syringe body 202, as shown in FIG. 24 and FIG. 25, a hubinsertion portion 204 is formed unitely connecting with the taper 206,and the hub insertion portion 204 has a small cylindrical portion 207.The small cylindrical portion 207 is formed unitedly connecting with thetaper 206, coaxial with the main cylindrical portion 203, and the insidediameter of the small cylindrical portion 207 is smaller than one of themain cylindrical portion 203.

An inner peripheral face 207a side of the small cylindrical portion 207is a hub insertion hole 204b. A hub stop rib 207d projecting for theaxis center YQ1 is formed in the hub insertion hole 204b. The hub stoprib 207d is annularly formed along the inner peripheral face 207a of thesmall cylindrical portion 207. The section of a plane including the axiscenter YQ1 of the hub stop rib 207d (that is, the section as shown inFIG. 24) is a circular arc.

On the other hand, on an outer peripheral face 207f side of the smallcylindrical portion 207, a stiffening rib 207c is annularly provided atthe position corresponding to the hub stop rib 207d putting the smallcylindrical portion 207 therebetween.

As shown in FIG. 20 or FIG. 25, an end wall 208, having an outsidediameter equal to one of the small cylindrical portion 207, formed inthe shape of a circular plate, is provided with the small cylindricalportion 207. The end wall 208 is provided united with the smallcylindrical portion 207 contacting a wall face 208b of the arrow YB sideof the end wall 208 and an end portion 207b of the arrow YA side of thesmall cylindrical portion 207 with each other. A hole 208a having acircular section is provided with the end wall 208 penetrating bothfront and back wall faces of the end wall 208 in the directions as shownby the arrows YA and YB such that the center is the axis center YQ1. Thearrow YA side of the hole 208a is taperingly formed such that thesectional inside diameter is made bigger for the direction as shown bythe arrow YA.

Three slits 250 are formed extending in the end wall 208 and the smallcylindrical portion 207, as shown in FIG. 20 or FIG. 21. The slits 250are formed extending in a radial direction with respect to the axiscenter YQ1, that is, in the directions as shown by arrows YC and YD inthe figure (The arrow YC direction is opposite to the arrow YDdirection.), communicating with the hole 208a provided at the end wall208 in the end wall 208, and are formed parallel to the directions asshown by the arrows YA and YB in the small cylindrical portion 207. Theslits 250 are formed on the arrow YA side rather than the hub stop rib207d and the stiffening rib 207c, not reaching the hub stop rib 207d andthe stiffening rib 207c.

Since the arrow YA side of the hub insertion portion 204 is divided intothree parts by the slits 250, the portions of the hub insertion portion204 formed the slits 250 are easy to be elastically enlarged in thedirection as shown by the arrow YC. That is, when the syringe assembly201 is assembled by inserting a hub 209 referred hereinafter into thesyringe Y100, the portions of the hub insertion portion 204 formed slits250 are elastically enlarged in the direction as shown by the arrow YCand the hole 208a of the end wall 208 is enlarged, thereby the hub 209referred hereinafter can be inserted into the hub insertion hole 204bthrough the hole 208a.

The hub insertion portion 204 is comprised as explained heretofore. Thesyringe Y100 is comprised such that the syringe support 205, and themain cylindrical portion 203 comprising the syringe body 202, the taper206 and the hub insertion portion 204 are unitedly formed.

The hub 209 made of resin, which is harder than the syringe Y100, isprovided with the hub insertion hole 204b of the hub insertion portion204. As shown in FIG. 24, FIG. 25 or FIG. 20, the hub 209 has a hub body290. A main pillar portion 210, which longitudinal direction is parallelto the directions as shown by the arrows YA and YB, which axis center isthe axis center YQ1, is provided in the shape of a cylinder with the hubbody 290.

A hub stop groove 210c is formed on the side of the outer peripheralface 210f of the main pillar portion 210. The hub stop groove 210c isannularly formed along the outer peripheral side of the main pillarportion 210.

On an end face 210a side of the arrow YA side of the main pillar portion210, a small pillar portion 211 is provided extending in the directionsas shown by the arrows YA and YB, coaxial with and united with the mainpillar portion 210. The hub 209 is provided such that the main pillarportion 210 of the hub 209 is inserted into the hub insertion hole 204bof the hub insertion portion 204, and the small pillar portion 211 ofthe hub 209 is inserted into the hole 208a of the end wall 208 so as topenetrate. The hub stop rib 207d of the hub insertion portion 204 andthe hub stop groove 210c of the hub 209 are at the positionscorresponding to and adjusting to each other, and then the hub stop rib207d is engaged with the hub stop groove 210c inserting the top end sideon the arrow YD side thereof into the hub stop groove 210c which is atthe position corresponding and adjusting to one of the hub stop rib207d.

Since the width of the hub stop rib 207d in the directions as shown bythe arrows YA and YB is broader than one of the hub stop groove 210c inthe directions as shown by the arrows YA and YB, the hub stop rib 207dis engaged with the hub stop groove 210c abutting on opening ends 210e,210e of both sides of the arrows YA and YB of the hub stop groove 210cin seal portions 207e, 207e on the sides of the arrows YA and YB of thetop thereof.

The inner peripheral face 207a of the small cylindrical portion 207 isnot in contact with the outer peripheral face 210f of the hub 209 in theportions excluding the hub stop rib 207d, and a gap space 249 is formedbetween the inner peripheral face 207a and the outer peripheral face210f. That is, since contact between the inner peripheral face 207a sideof the hub insertion portion 204b and the hub 209 is executed onlybetween the hub stop rib 207d and the outer peripheral face 210f side ofthe hub 209, when the syringe assembly 201 is assembled by inserting thehub 209 into the syringe Y100, the hub 209 can be easily inserted intothe hub insertion portion 204. In addition, in case of the operation ofstoring a needle, described hereinafter, the hub 209 is easily pulledout of the hub insertion portion 204 (As long as insertion of the hub209 into the hub insertion portion 204 and pulling the hub 209 out ofthe hub insertion portion 204 can be easily executed, the portionsexcluding the hub stop rib 207d of the inner peripheral face 207a of thesmall cylindrical portion 207 may be in contact with the outerperipheral face 210f of the hub 209.).

An end face 210b of the arrow YB side of the main pillar portion 210 ofthe hub 209 is positioned on the arrow YA side rather than the boundarybetween the hub insertion hole 204b and the inside space 202a (that is,the boundary between the inside of the small cylindrical portion 207 andthe inside of the taper 206), and the space of the inside of the hubinsertion hole 204b on the arrow YB side rather than the end face 210bis a hole space 204a.

On the other hand, the hub insertion portion 204 is elastically deformedexpanding the small cylindrical portion 207 in the direction as shown bythe arrow YC in such a state that the hub 209 is provided with the hubinsertion hole 204b. That is, the restoring force by elastic deformationof the small cylindrical portion 207 is transferred to the hub 209through the hub stop rib 207d of the small cylindrical portion 207. Thatis, predetermined seal pressures by the restoring force are respectivelyacted between the hub stop rib 207d and the hub 209 in the portionsbetween the seal portion 207e and the opening end 210e of the hub stopgroove 210c in which both abut on each other, and then, the portionbetween the seal portion 207e and the opening end 210e is in a watertight state or an air tight state.

The rigidity of the hub stop rib 207 and the portion near thereof isincreased in the small cylindrical portion 207 by the stiffening rib207c which is at the position corresponding to the hub stop rib 207dputting the small cylindrical portion 207 therebetween, and then apredetermined restoring force by elastic deformation of the smallcylindrical portion 207 can be effectively obtained.

As shown in FIG. 24, FIG. 25 or FIG. 20., a needle insertion hole 212 isprovided with the hub 209. The needle insertion hole 212 is providedforming a circular opening 212a, which center is the axis center YQ1, atan end face 211a of the arrow YA side of the small pillar portion 211 ofthe hub 209, extending from the end face 211a in the direction as shownby the arrow YB. An end portion 212b of the arrow YB side of the needleinsertion hole 212 reaches the inside of the main pillar portion 210 andthe end portion 212b is in contact with a wall face 210d of the mainpillar portion 210. In the needle insertion hole 212, tapers areadequately formed such that the diameter of the needle insertion hole212 is made narrower for the direction as shown by the arrow YB.

On the other hand, a flow hole 213 is provided with the main pillarportion 210 of the hub 209 adjacent to the arrow YB side of the needleinsertion hole 212 (right side of the paper of FIG. 24). The flow hole213 is cylindrically formed such that its center is the axis center YQ1and its diameter is smaller than one of the end portion 212b of theneedle insertion hole 212. The flow hole 213 is provided forming acircular opening at the wall face 210d of the main pillar portion 210,communicating with the needle insertion hole 212.

A piston engagement hole 215, which section perpendicular to the axiscenter YQ1 is a circle, is provided with the main pillar portion 210 ofthe hub 209 communicating with and adjacent to the arrow YB side of theflow hole 213, coaxial with the axis center YQ1. The arrow YB side ofthe piston engagement hole 215 is open outside in the end face 210b ofthe main pillar portion 210.

The piston engagement hole 215 is comprised of two parts, an engagementholding portion 216 of the arrow YA side and an introducing portion 217of the arrow YB side. The engagement holding portion 216 is almostcylindrical shape, coaxial with the axis center YQ1, and both endportion sides of the arrows YA and YB thereof are taperingly formed suchthat each diameter is made narrower for the direction as shown by thearrow YA or arrow YB. The end portion side of the arrow YA side of theengagement holding portion 216 is communicated and connected with theflow hole 213.

The introducing portion 217 communicates with and is adjacent to the endportion of the arrow YB side of the engagement holding portion 216. Thediameter of the introducing portion 217 is made bigger for the directionas shown by the arrow YB. Then, the portion sandwitched between a wallface 216a facing the engagement holding portion 216 and a wall face 217afacing the introducing portion 217 of the main pillar portion 210 formsa projection 220 projecting for the axis center YQ1 with a boundaryportion 219 between the engagement holding portion 216 and theintroducing portion 217 as an apex.

On the other hand, as shown in FIG. 25 or FIG. 20, a needle 221 isinserted into the needle insertion hole 212 of the hub 209. The needle221 is inserted from the rear end portion side into the needle insertionhole 212 and the top end side is positioned outside of the syringe body202. The rear end of the needle 221 abuts on the wall face 210d formedon the arrow YB side of the needle insertion hole 212. The medium flowhole 221a provided penetrating from the top end to the rear end side ofthe needle 221 and the flow hole 213 are adjacent to and communicatewith each other in the directions as shown by the arrows YA and YB.

An adhesive 222 is injected into the needle insertion hole 212 fillingbetween the needle 221 and the hub 209 and is hardened.

The piston 223 is provided with the syringe assembly 201, as shown inFIG. 24 or FIG. 25 (FIG. 25 is a typical sectional view of the syringeassembly 201, but with respect to a piston body 225, an outer pressplate 227, an inner press plate 229, a packing support 230, a hubengagement portion 231, referred hereinafter, of the piston 223, theirsides are shown, not their sections, for convenience.)

The piston 223 has the bar-shaped piston body 225 extending in thedirections as shown by the arrows YA and YB. The piston body 225 iscomprised such that two congruent plate portions 225a, each which is aplate shaped rectangle especially long in the directions as shown by thearrows YA and YB, are unitedly cross provided with each other such thatthe sections thereof form the shape of a cross. The width perpendicularto the directions as shown by the arrows YA and YB of the plate face ofthe plate portion 225a is almost equal to the inside diameter in theengagement rib 203b of the main cylindrical portion 203, and the pistonbody 225 is inserted into the main cylindrical portion 203 through theopening end 203a from the arrow YA side of the piston body 225.

On each plate portion 225a of the piston body 225, notches 226 areformed from both side portions of respective plate portions 225a, 225ain the direction of the axis center (that is, the axis center YQ1) ofthe piston body 225 in the shape of a wedge near the direction as shownby the arrow YA. Four notches 226 are provided at the positions adjustedone another in the directions as shown by the arrows YA and YB.

The outer press plate 227 in the shape of a circular plate, which plateface is perpendicular to the directions as shown by the arrows YA andYB, is provided united with the piston body 225 on the end portion sideof the arrow YB side of the piston body 225.

The inner press plate 229 in the shape of a circular plate, which plateface is perpendicular to the directions as shown by the arrows YA andYB, is provided united and coaxial with the piston body 225 on the endportion side of the arrow YA side of the piston body 225 (Therefore, theinner press plate 229 is positioned inside of the main cylindricalportion 203.), and the diameter of the inner press plate 229 is almostequal to the inside diameter of the main cylindrical portion 203(Therefore, the diameter of the inner press plate 229 is bigger than theinside diameter in the engagement rib 203b of the main cylindricalportion 203.).

As shown in FIG. 25, the packing support 230 is provided with the innerpress plate 229 on the arrow YA side thereof. A pillar portion 230a inthe shape of a cylinder, extending in the directions as shown by thearrows YA and YB, is provided with the packing support 230, beingcoaxial with the inner press plate 229. The diameter of the pillarportion 230a is smaller than one of the inner press plate 229. Thepillar portion 230a is provided on the arrow YA side of the inner pressplate 229, being united with the inner press plate 229. As shown in FIG.24 or FIG. 25, an insertion pillar portion 230b in the shape of acylinder, extending in the directions as shown by the arrows YA and YBbeing coaxial with the pillar portion 230a, having an outside diameteralmost equal to the inside diameter of the small cylindrical portion207, is provided on the arrow YA side of the pillar portion 230a, beingunited with the pillar portion 230a.

The hub engagement portion 231 is provided on the arrow YA side of theinsertion pillar portion 230b. A pillar portion 231a in the shape of acylinder, extending in the directions as shown by the arrows YA and YB,is provided with the hub engagement portion 231, being coaxial with theinsertion pillar portion 230b. The diameter of the pillar portion 231ais smaller than one of the insertion pillar portion 230b. The pillarportion 231a is provided on the arrow YA side of the insertion pillarportion 230b, being united with the insertion pillar portion 230b. Aninsertion portion 231b in the shape of a hemi-sphere, which diameter isbigger than one of the pillar portion 231a, is provided on the arrow YAside of the pillar portion 231a, being united with the pillar portion231a facing a spherical face 231c side to the arrow YA side. A pluralityof grooves 232 in the shape of a stripe are provided with the insertionportion 231b, being parallel to the spherical face 231c, extending fromthe top portion of the arrow YA side to the arrow YB side.

The diameter of the pillar portion 231a is almost equal to the insidediameter in the boundary portion 219 of the piston engagement hole 215provided with the hub 209. Therefore, the diameter of the insertionportion 231b is bigger than one of the boundary portion 219. The size ofthe insertion portion 231b allows itself to be sufficiently insertedinto and to be held by the engagement holding portion 216 of the pistonengagement hole 215.

On the other hand, as shown in FIG. 24, a packing 233 made of flexibleresin, is supported with the packing support 230. The packing 233 has apacking body 235 which is inserted into inside of the main cylindricalportion 203 of the syringe Y100 so as to be adjusted. An engagement hole235a penetrating the packing body 235 in the directions as shown by thearrows YA and YB is provided with the packing body 235. The engagementhole 235a penetrates the pillar portion 230a of the packing support 230and a part of the insertion pillar portion 230b. That is, the packing233 engages with the packing support 230 such that the packing support230 penetrates the engagement hole 235a, thereby the packing 233 issupported by the packing support 230. A supporting face 235h,perpendicular to the directions as shown by the arrows YA and YB, isformed at the end portion of the arrow YB side of the packing body 235.The supporting face 235h abuts on the inner press plate 229 so as toeasily receive a force in the direction as shown by the arrow YA by theinner press plate 229. The packing 233 and the pillar portion 230a inthe engagement hole 235a are closely contacted with each other, and theportion therebetween is sealed against water or against air.

A hollow clearance space 235f is formed inside of the packing body 235,enclosing the engagement hole 235a from the arrow YC side and beingadjacent to and communicating with the engagement hole 235a (Therefore,the clearance space 235f is enclosed by the packing body 235 on thearrows YA, YB and YC sides thereof, and is contacted with the insertionpillar portion 230b of the packing support 230 on the arrow YD sidethereof.). The packing 233 and the insertion pillar portion 230b arecontacted with each other in the portion of the arrow YA side ratherthan the clearance space 235f, of the engagement hole 235a, but both arenot closely contacted with each other, that is, the portion therebetweenis not sealed against water or against air. That is, air or liquid canflow between the clearance space 235f and the outside of the arrow YAside of the packing body 235 through the engagement hole 235a.

The arrow YA side of the packing body 235 is a taper 235b. While theform of the inside of the taper 206 of the syringe body 202 is a taper,reducing the inside diameter at a predetermined rate K1 for thedirection as shown by the arrow YA, as described before, the form of thetaper 235b in a natural state is a taper, reducing the outside diameterat a predetermined rate K2, which is bigger than a predetermined rateK1. That is, the taper 235b is formed forming a remaining space 251between a surface 235e excluding the end portion 235d of the taper 235b(that is, liquid pressing face capable of pressing the injection medium)and the inner peripheral face 206a of the taper 206 when an end portion235d of the arrow YB side of the taper 235b in a natural state abuts onan inner peripheral face 206a of the taper 206 inside of the taper 206.

A part of the arrow YA side of the insertion pillar portion 230b of thepacking support 230 penetrating the engagement hole 235a furtherprojects on the arrow YA side rather than the taper 235b.

In such a state that the end portion 235d of the taper 235b is abuttedon the inside of the taper 206 of the syringe body 202 when the taper235b of the packing 233 is in a natural state, as shown in FIG. 24, theinsertion pillar portion 230b of the packing support 230 engaging withthe packing 233 is inserted into the hub insertion hole 204b of thesyringe body 202. The form of the packing 233 is set so as to becomesuch a state where the spherical face 231c of the insertion portion 231bof the hub engagement portion 231 contacts with the wall face 217afacing the introducing portion 217 of the piston engagement hole 215.

The outside diameter of the packing body 235 of the packing 233 isalmost equal to one of the inner press plate 229. However, on the outerperipheral side of the packing body 235, annular folds 235c are doubleformed along the outer periphery of the packing body 235 arranging in aline in the directions as shown by the arrows YA and YB. Therefore, thepacking 233 is inserted into the main cylindrical portion 203 of thesyringe body 202, reducing the portion near the fold 235c of the packingbody 235 in the direction for the axis center YQ1, that is, in thedirection as shown by the arrow YD by elastic deformation. That is, thepacking 233 and the main cylindrical portion 203 are closely contactedwith each other in the folds 235c and the inner peripheral face 203c,and the portion between the packing 233 and the main cylindrical portion203 is sealed against water or against air.

The outer peripheral side of the packing body 235, that is, the surfaceof the side where the folds 235c and the like are formed is a slidingface 235g facing the inner peripheral face 203c of the syringe body 202.The packing 233 contacts with the inner peripheral face 203c in thesliding face 235g. Since the inner peripheral face 203c and the slidingface 235g are smoothly formed, the piston 223 inserted the packing 233therein is free to slide and move in the directions as shown by thearrows YA and YB in the inside space 202a of the main cylindricalportion 203.

The syringe assembly 201 is comprised as before, and then the syringeassembly 201 is used and, after that, the syringe assembly 201 isdiscarded as follows.

At first, the needle 221 of the syringe assembly 201 is advanced into aninjection medium 252 in a medicine bottle (not shown), the piston 223 ispulled in the direction as shown by the arrow YB with respect to thesyringe body 202, and by differential pressure, the injection medium 252in the medicine bottle flows to a medium holding space 253 which is aspace on the needle 221 side rather than the piston 223 of the holespace 204a of the hub insertion portion 204 and the inside space 202a ofthe syringe body 202 passing through the medium flow hole 221a of theneedle 221, the flow hole 213 of the hub 209 and the piston engagementhole 215 so as to fill the syringe assembly 201 with the injectionmedium 252.

In case of filling with the injection medium 252, a differentialpressure force in the direction as shown by the arrow YB by differentialpressure between the outside and the medium holding space 253 acts onthe hub 209. However, the restoring force in the direction as shown bythe arrow YD which the hub insertion portion 204 has is set in such apredetermined size as described heretofore, thereby sealing between eachseal portion 207e and each opening end 210e of the arrow YA side and thearrow YB side is not disengaged between the hub insertion portion 204and the hub 209 against the maximum differential pressure forcepredicted.

After filling with the injection medium 252, the needle 221 of thesyringe assembly 201 is stuck into an injection portion of a patient.Subsequently, the outer press plate 227 of the piston 223 is pressed inthe direction as shown by the arrow YA so as to drive the piston 223with respect to the syringe body 202 in the direction as shown by thearrow YA. The injection medium 252 of the medium holding space 253 ispressurized so as to flow into the body in the injection portion of apatient through the piston engagement hole 215 of the hub 209, the flowhole 213, the medium flow hole 221a of the needle 221.

On this occasion, the injection medium 252 is pressurized and an actionforce by the pressure of the injection medium 252 is added to the hub209 in the direction as shown by the arrow YA from the end face 210bside of the hub 209 adjacent to the injection medium 252. However, therestoring force in the direction as shown by the arrow YD which the hubinsertion portion 204 has is set in such a predetermined size asdescribed heretofore, thereby sealing between each seal portion 207e andeach opening end 210e on the arrow YA side and the arrow YB side is notdisengaged between the hub insertion portion 204 and the hub 209 againstthe maximum action force predicted.

After a predetermined amount of the injection medium 252 flows into thebody in the injection portion of a patient, that is, after the piston223 is driven to the position where the end portion 235d of the taper235b of the packing 233 is abutted on the inside of the taper 206 of thesyringe body 202, and as shown in FIG. 24, the insertion portion 231b ofthe hub engagement portion 231 of the piston 223 abuts on the wall face217a in the introducing hole 217 of the piston engagement hole 215 ofthe hub 209, that is, to an injection end position YP2 in the figure,the whole syringe assembly 201 is pulled in the direction as shown bythe arrow YB to a patient, and the needle 221 is pulled out of theinjection portion of a patient.

After the needle 221 is pulled out, the operation of storing the needleis executed as follows.

In the operation of storing the needle, the engagement operation betweenthe piston 223 and the hub 209 is executed as follows.

That is, the outer press plate 227 of the piston 223 is further pressedwith fingers in the direction as shown by the arrow YA so as to pressthe piston body 225 in the direction as shown by the arrow YA, and thenthe insertion pillar portion 230b of the packing support 230 and the hubengagement portion 231 are fed in the direction as shown by the arrow YAin the hub insertion hole 204b.

Just before start of the operation of storing the needle, the piston 223is positioned such that the taper 235b in a natural state is positionedcorresponding to the inside of the taper 206, the end portion 235d ofthe arrow YB side of the taper 235b abuts on the inner peripheral face206a of the taper 206, and the remaining space 251 is formed between thesurface 235e excluding the end portion 235d of the taper 235b and theinner peripheral face 206a of the taper 206. Therefore, by pressingpressure in the direction as shown by the arrow YA of the piston body225, in the packing 233, the portion on the arrow YB side from theportion near the end portion 235d abutting on the taper 206 iscompressed in the directions as shown by the arrows YB and YD, and theother part is pressed out in the direction as shown by the arrow YAmaking use of the remaining space 251 in such a manner that the surface235e approaches the taper 206. Therefore, since the quantity of elasticcompression in the packing 233 is extremely reduced by the remainingspace 251, the piston 223 can be operated with extremely small force.

In addition, the clearance space 235f is formed inside of the packingbody 235, the clearance space 235f is reduced with the packing body 235when the packing body 235 is elastically compressed. Therefore, sincethe quantity of elastic compression in the packing 233 is reduced by theclearance space 235f, the piston 233 can be operated with extremelysmall force.

As shown in FIG. 24, just before start of the operation of storing theneedle, the hole space 204a between the end face 210b of the hub 209 andthe insertion pillar portion 230b of the piston 223 side (that is, themedium holding space 253) and the remaining space 251 (that is, themedium holding space 253) are filled with the remaining injection medium252. The operation of storing the needle is started, the piston 223 ispressed and moved in the direction as shown by the arrow YA as describedheretofore, thereby the remaining injection medium 252 is pressurized.However, a plurality of grooves 232 are provided with the insertionportion 231b, as described heretofore, and then these grooves 232 arenot closed when the insertion portion 231b and the wall face 217a areabutted on each other by pressing. Therefore, when the insertion portion231b and the wall face 217a are abutted on each other by pressing, thehole space 204a or the remaining space 251 side and the engagementholding portion 216 side communicate with the grooves 232. The remaininginjection medium 252 pressurized of the hole space 204a or the remainingspace 251 flows to the engagement holding portion 216 side through thesegrooves 232 (This is because the injection medium 252 of the remainingspace 251 can flow to the hole space 204a side passing between theinsertion pillar portion 230b and the small cylindrical portion 207since the portion between the insertion pillar portion 230b and thesmall cylindrical portion 207 is not water tight.), and furthermore, isexpelled outside through the flow hole 213 and the medium flow hole 221aof the needle 221. That is, when the operation of storing the needlestarts and the piston 223 is pressed and moved in the direction as shownby the arrow YA, the remaining injection medium 252 pressurized in thehole space 204a or the remaining space 251 is appropriately expelledoutside, and the pressure is not extremely increased. Therefore, theresistance by pressure of remaining injection medium 252 is notextremely acted on the piston 223, and then the piston 223 is pressedand moved in the direction as shown by the arrow YA with extremely smallforce.

While the packing 233 is elastically reduced, the insertion pillarportion 230b of the packing support 230 and the hub engagement portion231 are pressed and moved in the direction as shown by the arrow YA inthe hub insertion portion 204b, and the insertion portion 231b of thehub engagement portion 231 is pressed and moved in the direction asshown by the arrow YA from the introducing portion 217 of the pistonengagement hole 215 for the engagement holding portion 216.

That is, the piston 223 is pressed and moved in the direction as shownby the arrow YA, thereby the insertion portion 231b is pressed to thewall face 217a in the introducing portion 217. However, the arrow YAside of the insertion portion 231b is the spherical face 231c, then theinsertion portion 231b is formed in such a manner that the sectionperpendicular to the axis center YQ1 is reduced for the direction asshown by the arrow YA. Then, the insertion portion 231b is pressed tothe wall face 217a in this spherical face 231c. In addition, theintroducing portion 217 is taperingly formed reducing the inside thereoffor the direction as shown by the arrow YA. Therefore, the insertionportion 231b is pressed in the direction as shown by the arrow YA in theintroducing portion 217, thereby stress by pressing pressurerespectively acting between the insertion portion 231b and theprojection 220 forming the wall face 217a respectively effectively actsin such a manner that for the insertion portion 231b the cross sectionperpendicular to the axis center YQ1 is elastically reduced, and for theprojection 220, the inside of the introducing portion 217 is elasticallyenlarged in the direction as shown by the arrow YC. As a result, thecross section perpendicular to the axis center YQ1 of the insertionportion 231b is reduced and the inside of the introducing portion 217 isenlarged in the direction as shown by the arrow YC, thereby theinsertion portion 231b pressed in the direction as shown by the arrow YAmoves in the direction as shown by the arrow YA in the introducingportion 217.

Furthermore, the piston 223 is pressed in the direction as shown by thearrow YA so as to move the insertion portion 231b in the direction asshown by the arrow YA in the introducing portion 217. Therefore, theinsertion portion 231b is moved on the engagement holding portion 216side passing through the boundary portion 219 between the introducingportion 217 and the engagement holding portion 216 from the arrow YAside thereof, and the insertion portion 231b is completely inserted intothe engagement holding portion 216, thereby the pressing of the piston223 is stopped. The insertion portion 231b is completely inserted intothe engagement holding portion 216, thereby the hub engagement portion231 and the piston engagement hole 215 are engaged with each other, andthen the operation of engagement between the piston 223 and the hub 209finishes.

On this occasion, pressing pressure force in the direction as shown bythe arrow YA acts on the insertion portion 231b, thereby pressingpressure force in the direction as shown by the arrow YA also acts onthe hub 209. However, the hub 209 is supported or can be supported inthe direction as shown by the arrow YB with the hand supporting thesyringe body 202 through the hub stop rib 207d of the hub insertionportion 204 or the end wall 208. Therefore, the hub 209 is not almostmoved in the direction as shown by the arrow YA or the like if receivingpressing pressure force, and the hub 209 is not pulled out of the hole208a of the end wall 208 in the direction as shown by the arrow YA.

Subsequently, the piston 223 is pulled against the syringe body 202 inthe direction as shown by the arrow YB with a predetermined pullingforce. That is, an action force in the direction as shown by the arrowYB by a predetermined pulling force acts on the piston 223 and theinsertion portion 231b of the hub engagement portion 231. The restoringforce in the direction as shown by the arrow YD which the hub insertionportion 204 has is set in a predetermined size, as described heretofore,thereby the sealing between each seal portion 207e and each opening end210e on the arrow YA side and on the arrow YB side is disengaged betweenthe hub insertion portion 204 and the hub 209 against the action forcein the direction as shown by the arrow YB by a predetermined pullingforce. Therefore, the sealing between the hub stop rib 207d and the hubstop groove 210c is disengaged. The hub stop rib 207d and the hub stopgroove 210c are disengaged from each other and the hub 209 is furtheradvanced in the direction as shown by the arrow YB, and then the hub 209is pulled until it is completely pulled out of the hub insertion hole204b in the direction as shown by the arrow YB.

On this occasion, since the gap space 249 is formed between the hub 209and the hub insertion hole 204b, contact between the hub 209 and thesmall cylindrical portion 207 is executed only through the hub stop rib207d portion, and the pulling operation can be easily executed with asmall force after the hub stop rib 207d and the hub stop groove 210c aredisengaged from each other.

The piston 223 is further pulled in the direction as shown by the arrowYB in such a manner that the needle 221 inserted and fixed on the arrowYA side of the hub 209 is inserted into the hub insertion hole 204b inthe direction as shown by the arrow YB from the hole 208a of the endwall 208 and further inserted into the inside space 202a of the maincylindrical portion 203 in the direction as shown by the arrow YB, andthe top end of the needle 221 is completely inserted into the insidespace 202a.

As shown in FIG. 26, the piston 223 is further pulled until the innerpress plate 229 abuts on the engagement rib 203b of the main cylindricalportion 203 of the syringe body 202, and then the piston 223 is stopped.

Then, the notch 226 of the piston body 225 is positioned near theopening end 203a of the syringe body 202. Subsequently, a force in thedirection as shown by the arrow YC is given to the piston 223. A forcein the direction as shown by the arrow YC is added to the piston 223with respect to the syringe body 202, thereby the piston body 225 isbent in the notch 226 which structure is relatively weak against bendingstress in the piston body 225, and the piston body 225 is divided intothe arrow YA side portion and the arrow YB side portion forming aboundary by the notch 226.

Subsequently, the portion of the syringe body 202 side bent and takenand the portion of the outer press plate 227 of the piston 223 aredisposed of so as to be discarded. Since the needle 221 is completelyinserted and stored in the inside space 202a of the syringe body 202being held with the top end portion of the piston 223 remaining in theinside space, there is no fear of hurting hands or the like and beingsecondarily infected from a wound by the needle 221. Therefore, wastedisposal can be safely executed. As described before, the operation ofstoring the needle finishes and the use of the syringe assembly 201 andwaste disposal after use all finish.

In the above-mentioned embodiment, the clearance space 235f of thepacking 233 is formed communicating outside of the packing 233 throughthe engagement hole 235a and the like. However, the clearance space 235fmay be formed not communicating with outside of the packing 233, thatis, inside of the packing 233 as long as the clearance space 235f can bereduced and changed in size when the packing 233 is compressed.

In addition, in the above-mentioned embodiment, the clearance space 235fof the packing 233 is formed being adjacent to the engagement hole 235a.However, as long as the clearance space 235f is formed inside of thepacking 233, and between the engagement hole 235a and the sliding face235g, for instance, the clearance space 235f may be formed being open tothe supporting face 235h of the packing body 235, as shown by thetwo-dot chain line of FIG. 24, that is, may be formed adjacent to theinner press plate 229.

In addition, in order to prevent entering the injection medium 252 andair into the clearance space 235f, the clearance space 235f may befilled with soft material, such as rubber, soft plastics, porous rubberhaving flexibility, porous plastics, which is softer than the packing233.

In addition, in the above-mentioned embodiment, the piston sideengagement means is the hub engagement portion 231 in the shape of aprojection, and the hub side engagement means is the piston engagementhole 215 in the shape of a hole. However, the piston side engagementmeans may be formed as a hole and the hub side engagement means may beformed as a projection as long as the piston side engagement means andthe hub side engagement means can be engaged with each other.

A syringe assembly 301 just before an injection action, or in such astate that a needle and a syringe are connected with each other, has asyringe Z100 made of resin, as shown in FIG. 28. A syringe body 302 isprovided with the syringe Z100 (FIG. 28 is a typical cross section ofthe syringe assembly 301, but a side is shown in a part of a piston 323,described hereinafter, not the section, for convenience.). A maincylindrical portion 303, cylindrically formed, is provided with thesyringe body 302. A direction of an axis center of the main cylindricalportion 303, that is, the reciprocating directions parallel to an axiscenter ZQ1 are an arrow ZA direction in the figure (or the leftdirection of the paper of FIG. 28.) and an arrow ZB direction (or theright direction of the paper of FIG. 28).

On the outer periphery side of the main cylindrical portion 303, asyringe support 305 is provided near an opening end 303a of the arrow ZBside of the main cylindrical portion 303 (the right side of the paper ofFIG. 28), in such a manner as forming a flange of the main cylindricalportion 303. On an inner peripheral face 303c side of the maincylindrical portion 303, an engagement rib 303b, projecting in thedirection for the axis center ZQ1 of the main cylindrical portion 303,that is, the direction as shown by an arrow ZD of the figure, isannularly formed near the opening end 303a along the inner peripheralface 303c.

As shown in FIG. 27 or FIG. 28, on the arrow ZA side of the maincylindrical portion 303 a taper 306, which inside diameter is reduced ata predetermined rate of K1 for the direction as shown by the arrow ZA,in the shape of a funnel, is formed unitedly connecting with the maincylindrical portion 303.

The inside of the main cylindrical portion 303 and the inside of thetaper 306 communicate with each other in the directions as shown by thearrows ZA and ZB, and the space combined both insides is an inside space302a of the syringe body 302.

On the side of the arrow ZA of the taper 306, that is, on the side ofthe top of the syringe body 302, as shown in FIG. 27 and FIG. 28, a hubinsertion portion 307 is formed unitely connecting with the taper 306.The hub insertion portion 307 is cylindrically formed, coaxial with themain cylindrical portion 303. The inside diameter of the hub insertionportion 307 is smaller than one of the main cylindrical portion 303.

An inner peripheral face 307a side of the hub insertion portion 307 is ahub insertion hole 307b. A hub stop rib 307d projecting for the axiscenter ZQ1 is formed in the hub insertion hole 307b. The hub stop rib307d is annularly formed along the inner peripheral face 307a. Thesection of a plane including the axis center ZQ1 of the hub stop rib307d (that is, the section as shown in FIG. 27 or FIG. 28) is a circulararc.

On the other hand, on an outer peripheral face 307f side of the hubinsertion portion 307, a hub fixed member engagement groove 307c isannularly provided along the outer peripheral face 307f.

The top portion of the arrow ZA side of the hub insertion portion 307 isan opening end 307g. The inside diameter of the hub insertion portion307 (in such a state that it is not elastically deformed) is set as apredetermined size extending from the end portion of the arrow ZB sidewhich is a boundary between the hub insertion portion 307 and the taper306 to the end portion of the arrow ZA side which is the opening end307g excluding the hub stop rib 307d.

The hub insertion portion 307 is comprised as described heretofore. Thesyringe Z100 is comprised such that the syringe support 305, the maincylindrical portion 303 comprising the syringe body 302, the taper 306and the hub insertion portion 307 are unitedly formed.

A needle assembly unit 360 is connected with the syringe Z100. Theneedle assembly unit 360 is comprised of a hub 309, a needle 321 and ahub fixed member 361, as shown in FIG. 27.

The hub 309 of the needle assembly unit 360 is provided with the hubinsertion hole 307b of the hub insertion portion 307 of the syringeZ100. The hub 309 has a hub body 310, as shown in FIG. 27. The hub body310, which longitudinal direction is parallel to the directions as shownby the arrows ZA and ZB, is formed in the shape of a cylinder which axiscenter is the axis center ZQ1. The outside diameter is an outsidediameter ZL1 on the arrow ZB side and an outside diameter ZL1' which issmaller than the outside diameter ZL1 on the arrow ZA side. That is, thehub body 310 is formed in the shape of a cylinder having a cavernousportion 310g by difference of the outside diameter. A hub stop groove310c is formed on the outer peripheral face 310f side of the portion ofthe outside diameter ZL1 of the hub body 310. The hub stop groove 310cis annularly formed along the outer peripheral face 310f.

An engagement holding pillar portion 311 having an outside diameter ZL2being smaller than the outside diameter ZL1', extending in thedirections as shown by the arrows ZA and ZB, is provided being unitedand coaxial with the hub body 310 on an end face 310a side of the arrowZA side of the hub body 310 (that is, the arrow ZA side of the portionof the outside diameter ZL1' of the hub body 310).

The hub 309 is provided such that the portion of the outside diameterZL1 of the hub body 310 is inserted into the hub insertion hole 307b ofthe hub insertion portion 307, and the portion of the outside diameterZL1' of the hub body 310 and the engagement holding pillar portion 311project outside of the opening end 307g, that is, on the arrow ZA side.The hub stop rib 307d of the hub insertion portion 307 and the hub stopgroove 310c of the hub 309 are at the positions corresponding to andadjusting to each other, and then the hub stop rib 307d is engaged withthe hub stop groove 310c inserting the top end side on the arrow ZD sidethereof into the hub stop groove 310c which is at the positioncorresponding and adjusting to one of the hub stop rib 307d.

Since the width of the hub stop rib 307d in the directions as shown bythe arrows ZA and ZB is broader than one of the hub stop groove 310c inthe directions as shown by the arrows ZA and ZB, as shown in FIG. 27,the hub stop rib 307d is engaged with the hub stop groove 310c abuttingon opening ends 310e, 310e of both sides of the arrows ZA and ZB of thehub stop groove 310c in seal portions 307e, 307e on the sides of thearrows ZA and ZB of the top thereof.

The inner peripheral face 307a of the hub insertion portion 307 is notin contact with the outer peripheral face 310f of the hub 309 in theportions excluding the hub stop rib 307d, and a gap space 312 is formedbetween the inner peripheral face 307a and the outer peripheral face310f. That is, since contact between the inner peripheral face 307a sideof the hub insertion portion 307 and the hub 309 is executed onlybetween the hub stop rib 307d and the outer peripheral face 310f side ofthe hub 309, when the hub 309 is inserted into the syringe Z100, the hub309 can be easily inserted into the hub insertion portion 307. Inaddition, in case of the operation of storing a needle, describedhereinafter, the hub 309 is easily pulled out of the hub insertionportion 307 (As long as insertion of the hub 309 into the hub insertionportion 307 and pulling of the hub 309 out of the hub insertion portion307 can be easily executed, the portions excluding the hub stop rib 307dof the inner peripheral face 307a of the hub insertion portion 307 maybe in contact with the outer peripheral face 310f of the hub 309.).

An end face 310b of the arrow ZB side of the hub body 310 is positionedon the arrow ZA side rather than the boundary between the hub insertionhole 307b and the inside space 302a (that is, the boundary between theinside of the hub insertion portion 307 and the inside of the taper306), and the space of the inside of the hub insertion hole 307b on thearrow ZB side rather than the end face 310b is a hole space 307h.

On the other hand, the hub insertion portion 307 is elastically deformedexpanding in the direction as shown by an arrow ZC in such a state thatthe hub 309 is provided with the hub insertion hole 307b. That is, therestoring force by elastic deformation of the hub insertion portion 307is transferred to the hub 309 through the hub stop rib 307d of the hubinsertion portion 307. That is, predetermined seal pressures by therestoring force are respectively acted between the hub stop rib 307d andthe hub 309 in the portions between the seal portion 307e and an openingend 310e of the hub stop groove 310c in which both abut on each other,and then, the portion between the seal portion 307e and the opening end310e is in a water tight state or an air tight state.

As shown in FIG. 27, a needle insertion hole 313 is provided with thehub 309. The needle insertion hole 313 is provided forming a circularopening 313a, which center is the axis center ZQ1, at an end face 311aof the arrow ZA side of the engagement holding pillar portion 311 of thehub 309, extending from the end face 311a in the direction as shown bythe arrow ZB. An end portion 313b of the arrow ZB side of the needleinsertion hole 313 reaches the inside of the hub body 310 and the endportion 313b is in contact with a wall face 310d of the hub body 310. Inthe needle insertion hole 313, tapers are adequately formed such thatthe diameter of the needle insertion hole 313 is made narrower for thedirection as shown by the arrow ZB.

On the other hand, a flow hole 313c is provided with the hub body 310adjacent to the arrow ZB side of the needle insertion hole 313 (rightside of the paper of FIG. 27). The flow hole 313c is cylindricallyformed such that its center is the axis center ZQ1 and its diameter issmaller than one of the end portion 313b of the needle insertion hole313. The flow hole 313c is provided forming a circular opening at thewall face 310d of the hub body 310, communicating with the needleinsertion hole 313.

A piston engagement hole 315, which section perpendicular to the axiscenter ZQ1 is a circle, is provided with the hub body 310, communicatingwith and being adjacent to the arrow ZB side of the flow hole 313c,coaxial with the axis center ZQ1. The arrow ZB side of the pistonengagement hole 315 is open outside in the end face 310b of the hub body310.

The piston engagement hole 315 is comprised of two parts, an engagementholding portion 316 of the arrow ZA side and an introducing portion 317of the arrow ZB side. The engagement holding portion 316 is almostcylindrical shape, coaxial with the axis center ZQ1, and both endportion sides of the arrows ZA and ZB thereof are taperingly formed suchthat each diameter is made narrower for the direction as shown by thearrow ZA or arrow ZB. The end portion side of the arrow ZA side of theengagement holding portion 316 is communicated and connected with theflow hole 313c.

The introducing portion 317 communicates with and is adjacent to the endportion of the arrow ZB side of the engagement holding portion 316. Thediameter of the introducing portion 317 is made bigger for the directionas shown by the arrow ZB. Then, the portion sandwitched between a wallface 316a facing the engagement holding portion 316 and a wall face 317afacing the introducing portion 317 of the hub body 310 forms aprojection 320 projecting for the axis center ZQ1 with a boundaryportion 319 between the engagement holding portion 316 and theintroducing portion 317 as an apex.

On the other hand, as shown in FIG. 27, the needle 321 of the needleassembly unit 360 is inserted into the needle insertion hole 313 of thehub 309. The needle 321 is inserted from the rear end portion sidethereof into the needle insertion hole 313 and the top end side ispositioned outside of the syringe body 302. The rear end of the needle321 abuts on the wall face 310d formed on the arrow ZB side of theneedle insertion hole 313. A medium flow hole 321a provided penetratingfrom the top end to the rear end side of the needle 321 and the flowhole 313c are adjacent to and communicate with each other in thedirections as shown by the arrows ZA and ZB.

An adhesive 322 is injected into the needle insertion hole 313 fillingbetween the needle 321 and the hub 309 and is hardened.

As shown in FIG. 27, the hub fixed member 361 of the needle assemblyunit 360 has a fixed member body 361a capable of enclosing the openingend 307g of the hub insertion portion 307 and enclosing the portion nearthe opening end 307g of the hub insertion portion 307 from the outerperipheral face 307f side of the hub insertion portion 307. The fixedmember body 361a is comprised of a reaction wall portion 361d facing theopening end 307g of the hub insertion portion 307 and perpendicular inthe directions as shown by the arrows ZA and ZB, a cylindrical portion361e cylindrically formed enclosing the outer peripheral face 307f sideof the hub insertion portion 307, and a communicating portion 361fcommunicating between the reaction wall portion 361d and the cylindricalportion 361e. A hub engagement hole 362 penetrating the reaction wallportion 361d in the directions as shown by the arrows ZA and ZB isprovided with the reaction wall portion 361d. The communicating portion361f is taperingly formed such that the inside and outside diameters arereduced for the direction as shown by the arrow ZA.

That is, the hub fixed member 361 is installed on the hub insertionportion 307 inserting the portion near the opening end 307g side of thehub insertion portion 307 into a syringe insertion hole 361c which isinside of the cylindrical portion 361e, and is engaged with the hub 309penetrating the engagement holding pillar portion 311 of the hub 309 inthe hub engagement hole 362 formed at the reaction wall portion 361d.

In such a state that the engagement holding pillar portion 311penetrates the hub engagement hole 362, the fixed member body. 361a andthe engagement holding pillar portion 311 stress each other in thedirections as shown by the arrows ZC and ZD in the hub engagement hole362. By the force of this stress, a predetermined frictional force inthe directions as shown by the arrows ZA and ZB can be relatively actedin the contact portion between the fixed member body 361a and theengagement holding pillar portion 311 in the hub engagement hole 362between both 361a and 311.

On the other hand, a syringe engagement projection 363 is annularlyformed projecting along the inner peripheral face 361b on an innerperipheral face 361b side of the cylindrical portion 361e of the fixedmember body 361a. The position formed the syringe engagement projection363 corresponds and adjusts to one of the hub fixed member engagementgroove 307c of the hub insertion portion 307. Therefore, in such a statethat the fixed member body 361a is installed on the hub insertionportion 307, the position of the syringe engagement projection 363 andthe position of the hub fixed member engagement groove 307c arecorresponded and adjusted to each other. The syringe engagementprojection 363 is in a state of being inserted into and engaged with thehub fixed member engagement groove 307c. That is, the hub fixed member361 is installed in the hub insertion portion 307 engaging the syringeengagement projection 363 and the hub fixed member engagement groove307c with each other.

The side portion 363b, which is the portion of the arrow ZB side of anapex portion 363a positioned the nearest position to the arrow ZD sideof the syringe engagement projection 363, is formed gradually incliningin the direction by the arrow ZC for the direction as shown by the arrowZB. Then, when the hub fixed member 361 is installed in the hubinsertion portion 307 by pressing in the direction as shown by the arrowZB, the side portion 363b receives a force in the direction as shown bythe arrow ZC from the opening end 307g of the hub insertion portion 307abutting on the side portion 363b and the like. Therefore, thecylindrical portion 361e is effectively expanded in the direction asshown by the arrow ZC, thereby the hub fixed member 361 can be smoothlyinstalled in the hub insertion portion 307.

A side portion 363c which is the portion on the arrow ZA side of theapex portion 363a of the syringe engagement projection 363 is formed ina predetermined shape (in the shape of a wall face perpendicular to thedirections as shown by the arrows ZA and ZB in FIG. 27). Then, in such astate that the syringe engagement projection 363 and the hub fixedmember engagement groove 307c are engaged with each other, the sideportion 363c and the hub insertion portion 307 can add a force only inthe directions as shown by the arrows ZA and ZB to each other in theportion where the both 363c and 307 are abutted on each other, in thehub fixed member engagement groove 307c. That is, after the syringeengagement projection 363 and the hub fixed member engagement groove307c are engaged with each other, even if the hub fixed member 361 ispulled to the syringe Z100 in the direction as shown by the arrow ZA,the fixed member body 361a receives a reaction only in the direction asshown by the arrow ZB from the syringe Z100 through the syringeengagement projection 363. Therefore, since the cylindrical portion 361eis not expanded in the direction as shown by the arrow ZC, theengagement between the syringe engagement projection 363 and the hubfixed member engagement groove 307c is not disengaged.

The needle assembly unit 360 is comprised of the hub 309, the needle 321and the hub fixed member 361, as described heretofore. The needleassembly unit 360 is connected with the syringe Z100 such that the hub309 connected the needle 321 therewith is provided with the hubinsertion hole 307b and the hub fixed member 361 engaged the hub 309therewith is installed in the hub insertion portion 307.

The piston 323 is provided with the syringe assembly 301, as shown inFIG. 28 (FIG. 28 is a typical sectional view of the syringe assembly301, but with respect to a piston body 325, an outer press plate 327, aninner press plate 329, a packing support 330, a hub engagement portion331, referred hereinafter, of the piston 323, their sides are shown, nottheir sections, for convenience.)

The piston 323 has the bar-shaped piston body 325 extending in thedirections as shown by the arrows ZA and ZB. The piston body 325 iscomprised such that two congruent plate portions 325a, each which is aplate shaped rectangle especially long in the directions as shown by thearrows ZA and ZB, are unitedly cross provided with each other such thatthe sections thereof form the shape of a cross. The width perpendicularto the directions as shown by the arrows ZA and ZB of the plate face ofthe plate portion 325a is almost equal to the inside diameter in theengagement rib 303b of the main cylindrical portion 303, and the pistonbody 325 is inserted into the main cylindrical portion 303 through theopening end 303a from the arrow ZA side of the piston body 325.

On each plate portion 325a of the piston body 325, notches 326 areformed from both side portions of the respective plate portions 325a,325a in the direction of the axis center (that is, the axis center ZQ1)of the piston body 325 in the shape of a wedge near the direction asshown by the arrow ZA. Four notches 326 are provided at the positionsadjusted one another in the directions as shown by the arrows ZA and ZB.

The outer press plate 327 in the shape of a circular plate, which plateface is perpendicular to the directions as shown by the arrows ZA andZB, is provided united with the piston body 325 on the end portion sideof the arrow ZB side of the piston body 325.

The inner press plate 329 in the shape of a circular plate, which plateface is perpendicular to the directions as shown by the arrows ZA andZB, is provided united and coaxial with the piston body 325 on the endportion side of the arrow ZA side of the piston body 325 (Therefore, theinner press plate 329 is positioned inside of the main cylindricalportion 303.), and the diameter of the inner press plate 329 is almostequal to the inside diameter of the main cylindrical portion 303(Therefore, the diameter of the inner press plate 329 is bigger than theinside diameter in the engagement rib 303b of the main cylindricalportion 303.).

As shown in FIG. 27, the packing support 330 is provided with the innerpress plate 329 on the arrow ZA side thereof. A pillar portion 330a inthe shape of a cylinder, extending in the directions as shown by thearrows ZA and ZB, is provided with the packing support 330, beingcoaxial with the inner press plate 329. The diameter of the pillarportion 330a is smaller than one of the inner press plate 329. Thepillar portion 330a is provided on the arrow ZA side of the inner pressplate 329, being united with the inner press plate 329. As shown in FIG.27, an insertion pillar portion 330b in the shape of a cylinder,extending in the directions as shown by the arrows ZA and ZB beingcoaxial with the pillar portion 330a, having an outside diameter almostequal to the inside diameter of the hub insertion portion 307, isprovided on the arrow ZA side of the pillar portion 330a, being unitedwith the pillar portion 330a.

The hub engagement portion 331 is provided on the arrow ZA side of theinsertion pillar portion 330b. A pillar portion 331a in the shape of acylinder, extending in the directions as shown by the arrows ZA and ZB,is provided with the hub engagement portion 331, being coaxial with theinsertion pillar portion 330b. The diameter of the pillar portion 331ais smaller than one of the insertion pillar portion 330b. The pillarportion 331a is provided on the arrow ZA side of the insertion pillarportion 330b, being united with the insertion pillar portion 330b. Aninsertion portion 331b in the shape of a hemi-sphere, which diameter isbigger than one of the pillar portion 331a, is provided on the arrow ZAside of the pillar portion 331a, being united with the pillar portion331a facing an spherical face 331c side to the arrow ZA side. Aplurality of grooves 332 in the shape of a stripe are provided with theinsertion portion 331b, being parallel to the spherical face 331c,extending from the top portion of the arrow ZA side to the arrow ZBside.

The diameter of the pillar portion 331a is almost equal to the insidediameter in the boundary portion 319 of the piston engagement hole 315provided with the hub 309. Therefore, the diameter of the insertionportion 331b is bigger than one of the boundary portion 319. The side ofthe insertion portion 331b allows to be sufficiently inserted into andto be held by the engagement holding portion 316 of the pistonengagement hole 315.

On the other hand, as shown in FIG. 27, a packing 333 made of flexibleresin, is supported with the packing support 330. The packing 333 has apacking body 335 which is inserted into inside of the main cylindricalportion 303 of the syringe Z100 so as to adjust. An engagement hole 335apenetrating the packing body 335 in the directions as shown by thearrows ZA and ZB is provided with the packing body 335. The pillarportion 330a of the packing support 330 and a part of the insertionpillar portion 330b penetrate the engagement hole 335a. That is, thepacking 333 engages with the packing support 330 such that the packingsupport 330 penetrates the engagement hole 335a, thereby the packing 333is supported by the packing support 330. A supporting face 335h,perpendicular to the directions as shown by the arrows ZA and ZB, isformed at the end portion of the arrow ZB side of the packing body 335.The supporting face 335h abuts on the inner press plate 329 so as toeasily receive a force in the direction as shown by the arrow ZA by theinner press plate 329. The packing 333 and the pillar portion 330a inthe engagement hole 335a are closely contacted with each other, and theportion therebetween is sealed against water or against air.

A hollow clearance space 335f is formed inside of the packing body 335,enclosing the engagement hole 335a from the arrow ZC side and beingadjacent to and communicating with the engagement hole 335a (Therefore,the clearance space 335f is enclosed by the packing body 335 on thearrows ZA, ZB and ZC sides thereof, and is contacted with the insertionpillar portion 330b of the packing support 330 on the arrow ZD sidethereof.). The packing 333 and the insertion pillar portion 330b arecontacted with each other in the portion of the arrow ZA side ratherthan the clearance space 335f, of the engagement hole 335a, but both arenot closely contacted with each other, that is, the portion therebetweenis not sealed against water or against air. That is, air or liquid canflow between the clearance space 335f and the outside of the arrow ZAside of the packing body 335 through the engagement hole 335a.

The arrow ZA side of the packing body 335 is a taper 335b. While theform of the inside of the taper 306 of the syringe body 302 is a taper,reducing the inside diameter at a predetermined rate K1 for thedirection as shown by the arrow ZA, as described before, the form of thetaper 335b in a natural state is a taper, reducing the outside diameterat a predetermined rate K2, which is bigger than a predetermined rateK1. That is, the taper 335b is formed forming a remaining space 351between a surface 335e excluding the end portion 335d of the taper 335b(that is, liquid pressing face capable of pressing the injection medium)and the inner peripheral face 306a of the taper 306 when an end portion335d of the arrow ZB side of the taper 335b in a natural state abuts onan inner peripheral face 306a of the taper 306 inside of the taper 306.

A part of the arrow ZA side of the insertion pillar portion 330b of thepacking support 330 penetrating the engagement hole 335a furtherprojects on the arrow ZA side rather than the taper 335b.

In such a state that the end portion 335d of the taper 335b is abuttedon the inside of the taper 306 of the syringe body 302 when the taper335b of the packing 333 is in a natural state, as shown in FIG. 27, theinsertion pillar portion 330b of the packing support 330 engaging withthe packing 333 is inserted into the hub insertion hole 307b of thesyringe body 302. The form of the packing 333 is set so as to becomesuch a state that the spherical face 331c of the insertion portion 331bof the hub engagement portion 331 contacts with the wall face 317afacing the introducing portion 317 of the piston engagement hole 315.

The outside diameter of the packing body 335 of the packing 333 isalmost equal to one of the inner press plate 329. However, on the outerperipheral side of the packing body 335, annular folds 335c are doubleformed along the outer periphery of the packing body 335 arranging in aline in the directions as shown by the arrows ZA and ZB. Therefore, thepacking 333 is inserted into the main cylindrical portion 303 of thesyringe body 302, reducing the portion near the fold 335c of the packingbody 335 in the direction for the axis center ZQ1, that is, in thedirection as shown by the arrow ZD by elastic deformation. That is, thepacking 333 and the main cylindrical portion 303 are closely contactedwith each other in the folds 335c and the inner peripheral face 303c,and the portion between the packing 333 and the main cylindrical portion303 is sealed against water or against air.

The outer peripheral side of the packing body 335, that is, the surfaceof the side where the folds 335c and the like are formed is a slidingface 335g facing the inner peripheral face 303c of the syringe body 302.The packing 333 contacts with the inner peripheral face 303c in thesliding face 335g. Since the inner peripheral face 303c and the slidingface 335g are smoothly formed, the piston 323 inserted the packing 333therein is free to slide and move in the directions as shown by thearrows ZA and ZB in the inside space 302a of the main cylindricalportion 303.

The syringe assembly 301 just before an injection action, or in such astate that the needle 321 and the syringe Z100 are connected with eachother, is comprised, as described heretofore.

The syringe assembly 301 in the state of being stored, that is, in sucha state that the needle 321 and the syringe Z100 are not yet connectedwith each other, is as follows.

That is, the syringe assembly 301 in the state of being stored has thesyringe Z100. The piston 323 is provided with the syringe Z100 in such astate that it is inserted into the inside space 302a of the syringebody. In addition, the syringe assembly 301 in the state of being storedhas the needle assembly unit 360 in the state of being separated fromthe syringe Z100 (in the state of not being connected).

In the syringe assembly 301 in the state of being stored, a cap forstoring 370 is installed on the needle assembly unit 360, as shown inFIG. 29.

The cap for storing 370 has a cap body 700 cylindrically formed,extending in the directions as shown by the arrows ZA and ZB. An endportion side of the arrow ZA side of the cap body 700 is closed, and anend portion side of the arrow ZB side of the cap body 700 is open.Inside of the cap body 700, a cylindrical needle keeping space 370a isprovided extending from the end portion side of the arrow ZA side forthe direction as shown by the arrow ZB. On the arrow ZB side of theneedle keeping space 370a, a fixed member insertion space 370b capableof inserting the fixed member body 361a of the needle assembly unit 360therein is provided connecting with the needle keeping space 370a. Theend portion of the arrow ZB side of the fixed member insertion space370b is open outside forming an opening 370c at the cap body 700. Theopening 370c is open on the end portion side of the arrow ZB side of thecap body 700, as described heretofore,

The cap for storing 370 as described heretofore is installed on theneedle assembly unit 360 inserting the top end side of the needle 321into the needle keeping space 370a of the cap for storing 370 andinserting the fixed member body 361a into the fixed member insertionspace 370b of the cap for storing 370.

In such a state that the cap for storing 370 is installed, the cap body700 and the fixed member body 361a in the fixed member insertion space370b are fixed and closely contacted with each other in such a mannerthat a predetermined pressure is added in the directions as shown by thearrows ZC and ZD. The top end of the needle 321 is not in contact withthe cap body 700 in the needle keeping space 370a.

Since the fixed member insertion space 370b is formed in the shapecorresponding to the fixed member body 361a, the communicating portion361f of the fixed member body 361a in the state of being inserted intothe fixed member insertion space 370b abuts on an abutting surface 370dcorresponding to the communicating portion 361f of the surface on thefixed member insertion space 370b side of the cap body 700.

The syringe assembly 301 in the state of being stored, or in such astate that the needle 321 and the syringe Z100 are not yet connectedwith each other, is comprised as described heretofore.

As explained before, the hub 309 and the hub fixed member 361 are fixedsince the engagement holding pillar portion 311 engages with the hubengagement hole 362 so as to penetrate. Since the cap body 700 and thehub fixed member 361 are fixed, as described heretofore, the hub 309,the hub fixed member 361 and the cap for storing 370 are all fixed. Thatis, the hub 309 and the hub fixed member 361 are installed in the capfor storing 370 in the syringe assembly 301 in the state of beingstored, such that the needle 321 is stored in and inserted into the capfor storing 370, and the hub 309, the hub fixed member 361 and the capfor storing 370 are not separated from one another even by inadvertence.Therefore, storing maintenance of the needle assembly unit 360 can besafely executed.

Since the syringe assembly 301 just before injection action and thesyringe assembly 301 in the state of being stored are respectivelycomprised, as described before, and then the syringe assembly 301 in thestate of being stored just before injection action, that is, in thestate of use is used and, after that, the syringe assembly 301 isdiscarded as follows.

At first, an injection actor (not shown) elects the needle assembly unit360, installed the cap for storing 370 thereon, installed the needle 321having length and diameter suitable for injection therein, of thesyringe assemblies 301 in the state of being stored, and connects itwith the syringe Z100 inserted the piston 323 therein. In case ofconnection, after the end face 310b side of the hub 309 of the needleassembly unit 360 and the arrow ZB side of the syringe insertion hole361c of the hub fixed member 361, that is, an opening end 361g areadjusted to the opening end 307g of the hub insertion portion 307, theneedle assembly unit 360 is pressed with the cap for storing 370 on thesyringe Z100, that is, in the direction as shown by the arrow ZB. Sincethe abutting face 370d inside the cap for storing 370 and thecommunicating portion 361f of the hub fixed member 361 are abutted oneach other such that a stress can be added to one by the other in thedirections as shown by the arrows ZA and ZB, and the reaction wallportion 361d of the hub fixed member 361 and the end face 310a of thehub 309 are abutted on each other (or approach each other) such that astress can be added to one by the other in the directions as shown bythe arrows ZA and ZB, the hub fixed member 361 and the hub 309 arepressed in the direction as shown by the arrow ZB through the cap forstoring 370 when the cap for storing 370 is pressed in the direction asshown by the arrow ZB.

Since the outside diameter ZL1 of the hub body 310 is smaller than theinside diameter of the hub insertion portion 307 including the openingend 307g, the hub body 310 is inserted in the hub insertion hole 307b inthe direction as shown by the arrow ZB. By further continuing theinsertion, the outer peripheral side of the hub body 310 abuts on thehub stop rib 307d inside of the hub insertion portion 307. Since theinside diameter of the hub insertion portion 307 in the portion of thehub stop rib 307d is smaller than the outside diameter of the hub body,the side portion of the arrow ZA side of the hub stop rib 307d isabutted on the hub body. However, since the section of the hub stop rib307d is formed in the shape of an arc, pressing pressure force is addedby the portion near the end face of the hub body to the side portion,the pressing pressure force acts so as to be a force expanding anddeforming the hub insertion portion 307 in the direction as shown by thearrow ZC on the basis of the arc shape of the section and then, the hubinsertion portion 307 is expanded and deformed enlarging its insidediameter. The insertion is smoothly executed by expansion anddeformation. By further continuing the insertion, the position of thehub stop rib 307d and the position of the hub stop groove 310c in thedirections as shown by the arrows ZA and ZB are adjusted to each other.By adjustment, the hub stop rib 307d and the hub stop groove 310c areengaged with each other. The engagement means insertion of the hub 309into the hub insertion portion 307.

The opening end 307g side of the hub insertion portion 307 is insertedinto the syringe insertion hole 361c from the opening end 361g of thehub fixed member 361. Since the inside diameter of the cylindricalportion 361e of the fixed member body 361a is smaller than the outsidediameter of the hub insertion portion 307 in the portion of the syringeengagement projection 363, the portion near the opening end 307g of thehub insertion portion 307 abuts on the side face 363b of the syringeengagement projection 363. Since the side portion 363b is formedgradually inclining in the direction as shown by the arrow ZC for thedirection as shown by the arrow ZB, as described before, however, theside portion 363b receives a force in the direction as shown by thearrow ZC from the opening end 307g of the hub insertion portion 307abutting on the side portion 363b and the like. That is, since thecylindrical portion 361e is effectively expanded in the direction asshown by the arrow ZC by this force in the direction as shown by thearrow ZC, the hub insertion portion 307 is smoothly inserted into thehub fixed member 361. By further pressing the hub fixed member 361, thehub insertion portion 307 is further inserted into the syringe insertionhole 361c, and the position of the syringe engagement projection 363 andthe position of the hub fixed member engagement groove 307c of the hubinsertion portion 307 in the directions as shown by the arrows ZA and ZBare adjusted to each other. By adjustment, the syringe engagementprojection 363 and the hub fixed member engagement groove 307c areengaged with each other. This engagement means installation of the hubfixed member 361 in the syringe Z100.

As described heretofore, the hub 309 is inserted into the hub insertionportion 307 and the hub fixed member 361 is installed in the syringeZ100, thereby the needle assembly unit 360 is connected with the syringeZ100.

After connection, the syringe Z100 side is fixed and the cap for storing370 is taken away in the direction as shown by the arrow ZA. On thisoccasion, a frictional force against a predetermined pressure actsbetween the cap body 700 and the fixed member body 361a in thedirections as shown by the arrows ZA and ZB so as to keep the both 700and 361a. However, since the fixed member body 361a and the syringe Z100are fixed through the syringe engagement projection 363, as describedheretofore, only the cap for storing 370 is taken away being out of thehub fixed member 361. In this way, the syringe assembly 301 becomes tobe such a state that the needle 321 and the syringe Z100 are connectedwith each other, that is, the state just before use.

Subsequently, this syringe assembly 301 is used. That is, the needle 321of the syringe assembly 301 is advanced into an injection medium 352 ina medicine bottle (not shown), the piston 323 is pulled in the directionas shown by the arrow ZB with respect to the syringe body 302, and bydifferential pressure, the injection medium 352 in the medicine bottleis streamed to a medium holding space 353 on the needle 321 side ratherthan the piston 323, of the hole space 307h of the hub insertion portion307 and the inside space 302a of the syringe body 302 passing throughthe medium flow hole 321a of the needle 321, the flow hole 313c of thehub 309 and the piston engagement hole 315 so as to fill the syringeassembly 301 with the injection medium 352.

In case of filling of the injection medium 352, a differential pressureforce in the direction as shown by the arrow ZB by differential pressurebetween the outside and the medium holding space 353 acts on the hub309. However, the restoring force in the direction as shown by the arrowZD which the hub insertion portion 307 has is set as a predeterminedsize as described heretofore, thereby sealing between each seal portion307e and each opening end 310e of the arrow ZA side and the arrow ZBside is not disengaged between the hub 309 and the hub insertion portion307 against the maximum differential pressure force predicted.

After filling of the injection medium 352, the needle 321 of the syringeassembly 301 is stuck into an injection portion of a patient (notshown).

Subsequently, the outer press plate 327 of the piston 323 is pressed inthe direction as shown by the arrow ZA so as to drive the piston 323with respect to the syringe body 302 in the direction as shown by thearrow ZA. The injection medium 352 of the medium holding space 353 ispressurized so as to flow into the body in the injection portion of apatient (not shown) through the piston engagement hole 315 of the hub309, the flow hole 313c, the medium flow hole 321a of the needle 321.

On this occasion, the injection medium 352 is pressurized and an actionforce by the pressure of the injection medium 352 is added to the hub309 in the direction as shown by the arrow ZA from the end face 310bside of the hub 309 adjacent to the injection medium 352. However, therestoring force in the direction as shown by the arrow ZD which the hubinsertion portion 307 has is set in such a predetermined size asdescribed heretofore, thereby sealing between each seal portion 307e andeach opening end 310e on the arrow ZA side and the arrow ZB side is notdisengaged between the hub insertion portion 307 and the hub 309 againstthe maximum action force predicted.

After a predetermined amount of the injection medium 352 is flowed intothe body in the injection portion of a patient, that is, after thepiston 323 is driven to the position where the end portion 335d of thetaper 335b of the packing 333 is abutted on the inside of the taper 306of the syringe body 302, and as shown in FIG. 27, the insertion portion331b of the hub engagement portion 331 of the piston 323 abuts on thewall face 317a in the introducing hole 317 of the piston engagement hole315 of the hub 309, that is, to an injection end position ZP2 in thefigure, the whole syringe assembly 301 is pulled in the direction asshown by the arrow ZB to a patient (not shown), and the needle 321 ispulled out of the injection portion of a patient.

After the needle 321 is pulled out, the operation of storing the needleis executed as follows.

In the operation of storing the needle, the engagement operation betweenthe piston 323 and the hub 309 is executed as follows.

That is, the outer press plate 327 of the piston 323 is further pressedwith fingers in the direction as shown by the arrow ZA so as to pressthe piston body 325 in the direction as shown by the arrow ZA, and thenthe insertion pillar portion 330b of the packing support 330 and the hubengagement portion 331 are fed in the direction as shown by the arrow ZAin the hub insertion hole 307b.

Just before start of the operation of storing the needle, the piston 323is positioned such that the taper 335b in a natural state is positionedcorresponding to the inside of the taper 306, the end portion 335d ofthe arrow ZB side of the taper 335b abuts on the inner peripheral face306a of the taper 306, and a remaining space 351 is formed between thesurface 335e excluding the end portion 335d of the taper 335b and theinner peripheral face 306a of the taper 306. Therefore, by pressingpressure in the direction as shown by the arrow ZA of the piston body325, in the packing 333, the portion on the arrow ZB side from theportion near the end portion 335d abutting on the taper 306 iscompressed in the directions as shown by the arrows ZB and ZD, and theother portion is pressed out in the direction as shown by the arrow ZAmaking use of the remaining space 351 in such a manner that the surface335e approaches the taper 306. Therefore, since the quantity of elasticcompression in the packing 333 is extremely reduced by the remainingspace 351, the piston 323 can be operated with extremely small force.

In addition, since the clearance space 335f is formed inside of thepacking body 335, the clearance space 335f is also reduced with thepacking body 335 when the packing body 335 is elastically compressed.Therefore, since the quantity of elastic compression in the packing 333is reduced by the clearance space 335f, the piston 323 can be operatedwith extremely small force.

As shown in FIG. 27, just before start of the operation of storing theneedle, the hole space 307h between the end face 310b of the hub 309 andthe insertion pillar portion 330b of the piston 323 side (that is, themedium holding space 353) and the remaining space 351 (that is, themedium holding space 353) are filled with the remaining injection medium352. The operation of storing the needle is started, the piston 323 ispressed and moved in the direction as shown by the arrow ZA as describedheretofore, thereby the remaining injection medium 352 is pressurized.However, a plurality of grooves 332 are provided with the insertionportion 331b, as described heretofore, and then these grooves 332 arenot closed when the insertion portion 331b and the wall face 317a areabutted on each other by pressing. Therefore, when the insertion portion331b and the wall face 317a are abutted on each other by pressing, thehole space 307h or the remaining space 351 side and the engagementholding portion 316 side communicate with the grooves 332. The remaininginjection medium 352 pressurized of the hole space 307h or the remainingspace 351 flows to the engagement holding portion 316 side through thesegrooves 332 (This is because the injection medium 352 of the remainingspace 351 can flow to the hole space 307h side passing between theinsertion pillar portion 330b and the hub insertion portion 307 sincethe portion between the insertion pillar portion 330b and the hubinsertion portion 307 is not water tight.), and furthermore, is expelledoutside through the flow hole 313c and the medium flow hole 321a of theneedle 321. That is, when the operation of storing the needle starts andthe piston 323 is pressed and moved in the direction as shown by thearrow ZA, the remaining injection medium 352 pressurized in the holespace 307h or the remaining space 351 is appropriately expelled outside,and the pressure is not extremely increased. Therefore, the resistanceby pressure of remaining injection medium 352 is not extremely acted onthe piston 323, and then the piston 323 is pressed and moved in thedirection as shown by the arrow ZA with extremely small force.

While the packing 333 is elastically reduced, the insertion pillarportion 330b of the packing support 330 and the hub engagement portion331 are pressed and moved in the direction as shown by the arrow ZA inthe hub insertion portion 307b, and the insertion portion 331b of thehub engagement portion 331 is pressed and moved in the direction asshown by the arrow ZA from the introducing portion 317 of the pistonengagement hole 315 for the engagement holding portion 316.

That is, the piston 323 is pressed and moved in the direction as shownby the arrow ZA, thereby the insertion portion 331b is pressed to thewall face 317a in the introducing portion 317. However, the arrow ZAside of the insertion portion 331b is the spherical face 331c, then theinsertion portion 331b is formed in such a manner that the sectionperpendicular to an axis center ZQ1 is reduced for the direction asshown by the arrow ZA. Then, the insertion portion 331b is pressed tothe wall face 317a in this spherical face 331c. In addition, theintroducing portion 317 is taperingly formed reducing the inside thereoffor the direction as shown by the arrow ZA. Therefore, the insertionportion 331b is pressed in the direction as shown by the arrow ZA in theintroducing portion 317, thereby stress by pressing pressurerespectively acting between the insertion portion 331b and theprojection 320 forming the wall face 317a respectively effectively actsin such a manner that for the insertion portion 331b the cross sectionperpendicular to the axis center ZQ1 is elastically reduced, and for theprojection 320, the inside of the introducing portion 317 is elasticallyenlarged in the direction as shown by the arrow ZC. As a result, thecross section perpendicular to the axis center ZQ1 of the insertionportion 331b is reduced and the inside of the introducing portion 317 isenlarged in the direction as shown by the arrow ZC, thereby theinsertion portion 331b pressed in the direction as shown by the arrow ZAmoves in the direction as shown by the arrow ZA in the introducingportion 317.

Furthermore, the piston 323 is pressed in the direction as shown by thearrow ZA so as to further move the insertion portion 331b in thedirection as shown by the arrow ZA in the introducing portion 317.Therefore, the insertion portion 331b is moved on the engagement holdingportion 316 side passing through the boundary portion 319 between theintroducing portion 317 and the engagement holding portion 316 from thearrow ZA side thereof, and the insertion portion 331b is completelyinserted into the engagement holding portion 316, thereby the pressingof the piston 323 is stopped. The insertion portion 331b is completelyinserted into the engagement holding portion 316, thereby the hubengagement portion 331 and the piston engagement hole 315 are engagedwith each other, and then the operation of engagement between the piston323 and the hub 309 finishes.

On this occasion, a pressing pressure force in the direction as shown bythe arrow ZA acts on the insertion portion 331b, thereby a pressingpressure force in the direction as shown by the arrow ZA also acts onthe hub 309. However, the hub 309 is supported in the direction as shownby the arrow ZB with the hand supporting the syringe body 302 throughthe hub stop rib 307d of the hub insertion portion 307, through thesyringe body 302. Even if the hub 309 is not supported through the hubstop rib 307d, it can be supported with a hand supporting the syringebody 302 in the direction as shown by the arrow ZB, being supported theend face 310a of the hub 309 with the reaction wall portion 361d of thehub fixed member 361 and being supported the hub fixed member 361 withthe hub insertion portion 307 through the syringe engagement projection363. This is because in such a state that the syringe engagementprojection 363 and the hub fixed member engagement groove 307c areengaged with each other, as described before, the side portion 363c andthe hub insertion portion 307 can add a force to each other only in thedirections as shown by the arrows ZA and ZB in the portion where both363c and 307 are abutted on each other in the hub fixed memberengagement groove 307c. Therefore, if the hub fixed member 361 receivesa pressing pressure force in the direction as shown by the arrow ZA bythe hub 309 so as to pull to the syringe Z100 in the direction as shownby the arrow ZA, the fixed member body 361a receives a reaction only inthe direction as shown by the arrow ZB from the syringe Z100 through thesyringe engagement projection 363, and therefore, the cylindricalportion 361e is not expanded in the direction as shown by the arrow ZC,the syringe engagement projection 363 and the hub fixed memberengagement groove 307c are not disengaged from each other, and then, apressing pressure force by the hub 309 is completely transferred to thesyringe Z100 through the hub fixed member 361.

Therefore, the hub 309 is not almost moved in the direction as shown bythe arrow ZA and the like if receiving the pressing pressure force inthe direction as shown by the arrow ZA, and the hub 309 is not pulledout of the hub insertion portion 307 in the direction as shown by thearrow ZA.

Subsequently, the piston 323 is pulled with respect to the syringe body302 in the direction as shown by the arrow ZB with a predeterminedpulling force. That is, an action force in the direction as shown by thearrow ZB by a predetermined pulling force acts on the piston 323 and theinsertion portion 331b of the hub engagement portion 331. The restoringforce in the direction as shown by the arrow ZD which a hub insertionportion 304 has is set in such a predetermined size as one describedheretofore, thereby the sealing between each seal portion 307e and eachopening end 310e on the arrow ZA side and on the arrow ZB side isdisengaged between the hub 309 and the hub insertion portion 307 againstthe action force in the direction as shown by the arrow ZB by apredetermined pulling force. Therefore, the sealing between the hub stoprib 307d and the hub stop groove 310c is disengaged.

The hub fixed member 361 and the hub 309 are engaged with each othersuch that the engagement holding pillar portion 311 penetrates the hubfixed member 361. In addition, as described heretofore, a predeterminedpressure in the directions as shown by the arrows ZC and ZD acts betweenthe both 311 and 361, and by this pressure, a predetermined frictionalforce in the directions as shown by the arrows ZA and ZB acts betweenboth 311 and 361 so as to keep the both 311 and 361. However, since apredetermined pulling force when the hub 309 is pulled out is onedefeating the predetermined frictional force, the engagement holdingpillar portion 311 and the hub fixed member 361 are disengaged from eachother being pulled the engagement holding pillar portion 311 out of thehub fixed member 361.

The hub stop rib 307d and the hub stop groove 310c are disengaged fromeach other, the engagement holding pillar portion 311 and the hub fixedmember 361 are disengaged from each other, and the hub 309 is furtheradvanced in the direction as shown by the arrow ZB, and then the hub 309is pulled until it is completely pulled out of the hub insertion hole307b in the direction as shown by the arrow ZB.

On this occasion, since the gap space 312 is formed between the hub 309and the hub insertion hole 307b, contact between the hub 309 and the hubinsertion portion 307 is executed only through the hub stop rib 307dportion, and the pulling operation can be easily executed with a smallforce after the hub stop rib 307d and the hub stop groove 310c aredisengaged from each other.

The piston 323 is further pulled in the direction as shown by the arrowZB in such a manner that the needle 321 inserted and fixed on the arrowZA side of the hub 309 is inserted into the hub insertion hole 307b inthe direction as shown by the arrow ZB from the hub engagement hole 362of the hub fixed member 361 and the opening end 307g of the hubinsertion portion 307 and further inserted into the inside space 302a ofthe main cylindrical portion 303 in the direction as shown by the arrowZB, and the top end of the needle 321 is completely inserted into theinside space 302a.

As shown in FIG. 30, the piston 323 is further pulled until the innerpress plate 329 abuts on the engagement rib 303b of the main cylindricalportion 303 of the syringe body 302, and then the piston 323 is stopped.

Then, the notch 326 of the piston body 325 is positioned near theopening end 303a of the syringe body 302. Subsequently, a force in thedirection as shown by the arrow ZC is given to the piston 323. A forcein the direction as shown by the arrow ZC is added on the piston 323with respect to the syringe body 302, thereby the piston body 325 isbent in the notch 326 which structure is relatively weak against bendingstress in the piston body 325, and the piston body 325 is divided intothe arrow ZA side portion and the arrow ZB side portion forming aboundary by the notch 326.

Subsequently, the portion of the syringe body 302 side bent and takenand the portion of the outer press plate 327 of the piston 323 aredisposed of so as to be discarded. Since the needle 321 is completelyinserted and stored in the inside space. 302a of the syringe body 302being held with the top end portion of the piston 323 remaining in theinside space, there is no fear of hurting hands or the like and beingsecondarily infected from a wound by the needle 321. Therefore, wastedisposal can be safely executed. As described before, the operation ofstoring the needle finishes and the use of the syringe assembly 301 andwaste disposal after use all finish.

In the above-mentioned embodiment, the syringe engagement projection 363formed in the shape of a projection is formed at the hub fixed member361 of the needle assembly unit 360 as a syringe fixed means, and thehub fixed member engagement groove 307c formed in the shape of a grooveis formed at the hub insertion portion 307 of the syringe Z100 as thereaction fixed member engagement means. However, as long as the syringefixed means and the reaction fixed member engagement means may be formedsuch that both can be fixed and engaged with each other, any form ofboth is acceptable. For instance, the syringe fixed means may be formedin the shape of a groove, and the reaction fixed member engagement meansmay be formed in the shape of a projection. Alternatively, the syringefixed means and the reaction fixed member engagement means may be formedin the shape of a screw so as to engage with each other.

The present invention has been explained on the basis of the embodimentspresented herein. However, the embodiments which are described in thepresent specification are illustrative and not limiting. The scope ofthe invention is designated by the accompanying claims and is notrestricted by the descriptions of the specific embodiments. Accordingly,all the transformations and changes belonging to the claims are includedin the scope of the present invention.

I claim:
 1. A syringe assembly, comprising:a cylindrical syringe bodyforming a liquid holding space therein; a piston inside said syringebody, movable relative to the syringe body in an axial direction definedby said syringe body, along a center axis; said syringe body defining acylindrical hub installation space; a top edge of said syringe bodydefining an installation hole, said installation hole communicatingbetween said hub installation space and an outside of said syringe body;a hub for said syringe assembly having a hub body attachably anddetachably connected with said syringe body at the hub installationspace; a hub side engagement means provided on said hub body; a pistonside engagement means on the piston, facing said hub side engagementmeans of said hub so as to be inserted into and engaged with said hubside engagement means; whereby, after injection, said piston is movableaxially forward along the center axis so as to abut and engage saidpiston side engagement means of said piston with said hub sideengagement means of said hub body, whereupon the piston is movableaxially rearward so as to pull said hub body into said syringe bodytogether with said needle; wherein said hub body is substantiallycylindrical and capable of being linearly inserted into said hubinstallation space along said center axis of said hub body, and capableof being linearly pulled into said syringe body from said hubinstallation space in said direction of said center axis; a seal portioncomprising a projection having a first width along said center axis ofsaid hub body, annularly formed at an outer peripheral portion of saidhub body; a hub seal portion in the shape of a groove having a secondwidth narrower than said first width along the center axis of saidsyringe body, annularly formed at an inner peripheral face of saidsyringe body at said hub installation space, said projection of saidseal portion of said hub body being engageable with said groove of saidhub seal portion with a predetermined contact pressure; and a bypassmeans formed at said piston side engagement means so as to couplebetween an inner space of said hub side engagement means and said liquidholding space when said piston side engagement means and said hub areabutted on each other.
 2. The syringe assembly as set forth in claim 1,wherein said bypass means comprises a groove formed along a surface ofsaid piston side engagement means.
 3. The syringe assembly as set forthin claim 1, wherein said bypass means comprises a hole formed at saidpiston side engagement means.
 4. The syringe assembly as set forth inclaim 1, wherein said hub for said syringe assembly is directlyconnected with a needle.
 5. A syringe assembly, comprising:a cylindricalsyringe body forming a liquid holding space therein; a piston inside ofsaid syringe body, movable relative to the syringe body in an axialdirection defined by said syringe body, along a center axis; saidsyringe body defining a cylindrical hub installation space; a top edgeof said syringe body defining an installation hole, the installationhole communicating between said hub installation space and an outside ofsaid syringe body; a hub for said syringe assembly having a hub bodyattachably and detachably connected with said syringe body at the hubinstallation space and capable of being linearly pulled into saidsyringe body from said hub installation space in said direction of saidcenter axis; a hub side engagement means provided in said hub body; apiston side engagement means on the piston, facing said hub sideengagement means of said hub, so as to be inserted into and engaged withsaid hub side engagement means; whereby, after injection, said piston ismovable axially forward along the center axis so as to abut and engagesaid piston side engagement means of said piston with said hub sideengagement means of said hub body, whereupon the piston is movableaxially rearward so as to pull said hub body into said syringe bodytogether with said needle; wherein said hub body is substantiallycylindrical and capable of being linearly inserted into said hubinstallation hole along said center axis of said syringe body andcapable of being linearly pulled into said syringe body from said hubinstallation space in said direction of said center axis; a seal portioncomprising a groove having a first width along a center axis of said hubbody, annularly formed at an outer peripheral portion of said hub body;a hub seal portion in the shape of a projection having a second widthwider than said first width along the center axis of said syringe body,annularly formed at an inner peripheral face of said syringe body atsaid hub installation space, and said groove of said seal portion ofsaid hub body being engageable with said projection of said hub sealportion with a predetermined contact pressure forming a seal; and abypass means formed at said piston side engagement means so as to couplebetween an inner space of said hub side engagement means and said liquidholding space when said piston side engagement means and said hub areabutted on each other.
 6. The syringe assembly as set forth in claim 5,wherein said bypass means comprises a groove formed along a surface ofsaid piston side engagement means.
 7. The syringe assembly as set forthin claim 5, wherein said bypass means comprises a hole formed at saidpiston side engagement means.
 8. The syringe assembly as set forth inclaim 1, wherein said hub for said syringe assembly is directlyconnected with a needle.
 9. A syringe assembly, comprising:a cylindricalsyringe body forming a liquid holding space therein; a piston insidesaid syringe body, movable relative to the syringe body in an axialdirection defined by said syringe body, along a center axis; saidsyringe body defining a cylindrical hub installation space; a top edgeof said syringe body defining an installation hole, said installationhole communicating between said hub installation space and an outside ofsaid syringe body; a hub for said syringe assembly having a hub bodyattachably and detachably connected with said syringe body at the hubinstallation space, said hub body having means connectable with a needleon one end of the hub body and being capable of being linearly pulledinto said syringe body from said hub installation space in saiddirection of said center axis; a hub side engagement means provided onthe hub body on an opposite end side from said one end side; a pistonside engagement means on the piston, facing said hub side engagementmeans of said hub, so as to be inserted into and engaged with said hubside engagement means; whereby, after injection, said piston is movableaxially forward along the center axis of said syringe body so as to abutand engage said piston side engagement means of said piston with saidhub side engagement means of said hub body, whereupon the piston ismovable axially rearward so as to pull said hub body into said syringebody together with said needle; a holding portion annularly provided atan inner peripheral portion of said syringe body at said hubinstallation space; an installation taper portion having a reducinginner diameter proceeding toward a top edge side of said syringe body,annularly formed on the top edge side relative to said holding portionof said inner peripheral portion of said syringe body; wherein a heldportion is annularly formed at an outer peripheral portion of said hubbody; a seal taper portion having a reducing outer diameter proceedingtoward said one end of said hub body, annularly formed at an outerperipheral portion of said hub body between said held portion of saidhub body; said hub body of said hub being capable of insertion andinstallation into said hub installation space, contacting said sealtaper portion of said hub body with said installation taper portion andengaging both said held portion of said hub body and said holdingportion of said syringe body, to compress said seal raper portion ofsaid hub body and said held portion of said hub body to hold and sealthe hub body; and a bypass means formed at said piston side engagementmeans so as to couple between an inner space of said hub side engagementmeans and said liquid holding space when said piston side engagementmeans and said hub are abutted on each other.
 10. The syringe assemblyas set forth in claim 9, wherein said bypass means comprises a grooveformed along a surface of said piston side engagement means.
 11. Thesyringe assembly as set forth in claim 9, wherein said bypass meanscomprises a hole formed at said piston side engagement means.
 12. Asyringe assembly, comprising:a cylindrical syringe body forming a liquidholding space therein; a piston inside said syringe body, movablerelative to the syringe body in an axial direction defined by saidsyringe body, along a center axis; said syringe body defining acylindrical hub installation space; a top edge of said syringe bodydefining an installation hole, said installation hole communicatingbetween said hub installation space and an outside of said syringe body;a hub for said syringe assembly having a hub body attachably anddetachably connected with said syringe body at the hub installationspace; a needle directly connected to one end of said hub body, said hubbody being capable of being linearly pulled into said syringe body fromsaid hub installation space in said direction of said center axis; a hubside engagement means provided on the hub body on an opposite end fromsaid one end; a piston side engagement means on the piston, facing saidhub side engagement means of said hub, so as to be inserted into andengaged with said hub side engagement means; whereby, after injection,said piston is movable axially forward along the center axis of saidsyringe body so as to abut and engage said piston side engagement meansof said piston with said hub side engagement means of said hub body,whereupon the piston is movable axially rearward so as to pull said hubbody into said syringe body together with said needle; a holding portionannularly provided at an inner peripheral portion of said syringe bodyat said hub installation space; an installation taper portion having areducing inner diameter proceeding toward a top edge side of saidsyringe body, annularly formed on the top edge side relative to saidholding portion of said inner peripheral portion of said syringe body;wherein a held portion is annularly formed at an outer peripheralportion of said hub body; a seal taper portion having a reducing outerdiameter proceeding toward said one end of said hub body, annularlyformed at an outer peripheral portion of said hub body between said heldportion and said one end of said hub body; said hub body of said hubbeing capable of insertion and installation into said hub installationspace, contacting said seal taper portion of said hub body with saidinstallation taper portion and engaging both said held portion of saidhub body and said holding portion of said syringe body, to compress saidseal taper portion of said hub body and said held portion of said hubbody to hold and seal the hub body; and a bypass means formed at saidpiston side engagement means so as to couple between an inner space ofsaid hub side engagement means and said liquid holding space when saidpiston side engagement means and said hub are abutted on each other.